Merge pull request #1175 from Mbucari/master

Additional null safety

Source/AppScaffolding/AppScaffolding.csproj

@@ -2,7 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>net9.0</TargetFramework>
-    <Version>12.0.2.1</Version>
+    <Version>12.0.2.2</Version>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Octokit" Version="14.0.0" />

Source/ApplicationServices/LibraryCommands.cs

@@ -15,12 +15,13 @@ using Newtonsoft.Json.Linq;
 using Serilog;
 using static DtoImporterService.PerfLogger;
 
+#nullable enable
 namespace ApplicationServices
 {
     public static class LibraryCommands
     {
-        public static event EventHandler<int> ScanBegin;
+        public static event EventHandler<int>? ScanBegin;
-        public static event EventHandler<int> ScanEnd;
+        public static event EventHandler<int>? ScanEnd;
 
         public static bool Scanning { get; private set; }
         private static object _lock { get; } = new();
@@ -100,7 +101,7 @@ namespace ApplicationServices
         }
 
         #region FULL LIBRARY scan and import
-        public static async Task<(int totalCount, int newCount)> ImportAccountAsync(Func<Account, Task<ApiExtended>> apiExtendedfunc, params Account[] accounts)
+        public static async Task<(int totalCount, int newCount)> ImportAccountAsync(Func<Account, Task<ApiExtended>> apiExtendedfunc, params Account[]? accounts)
         {
             logRestart();
 
@@ -236,7 +237,7 @@ namespace ApplicationServices
         {
             var tasks = new List<Task<List<ImportItem>>>();
 
-           await using LogArchiver archiver
+           await using LogArchiver? archiver
                 = Log.Logger.IsDebugEnabled()
                 ? new LogArchiver(System.IO.Path.Combine(Configuration.Instance.LibationFiles, "LibraryScans.zip"))
                 : default;
@@ -266,13 +267,13 @@ namespace ApplicationServices
             return importItems;
         }
 
-        private static async Task<List<ImportItem>> scanAccountAsync(ApiExtended apiExtended, Account account, LibraryOptions libraryOptions, LogArchiver archiver)
+        private static async Task<List<ImportItem>> scanAccountAsync(ApiExtended apiExtended, Account account, LibraryOptions libraryOptions, LogArchiver? archiver)
         {
             ArgumentValidator.EnsureNotNull(account, nameof(account));
 
             Log.Logger.Information("ImportLibraryAsync. {@DebugInfo}", new
             {
-                Account = account?.MaskedLogEntry ?? "[null]"
+                Account = account.MaskedLogEntry ?? "[null]"
             });
 
             logTime($"pre scanAccountAsync {account.AccountName}");
@@ -294,7 +295,7 @@ namespace ApplicationServices
 				throw new AggregateException(ex.InnerExceptions);
             }
 
-            async Task logDtoItemsAsync(IEnumerable<AudibleApi.Common.Item> dtoItems, IEnumerable<Exception> exceptions = null)
+            async Task logDtoItemsAsync(IEnumerable<AudibleApi.Common.Item> dtoItems, IEnumerable<Exception>? exceptions = null)
             {
 				if (archiver is not null)
 				{
@@ -452,28 +453,28 @@ namespace ApplicationServices
         }
 
         /// <summary>Occurs when the size of the library changes. ie: books are added or removed</summary>
-        public static event EventHandler<List<LibraryBook>> LibrarySizeChanged;
+        public static event EventHandler<List<LibraryBook>>? LibrarySizeChanged;
 
         /// <summary>
         /// Occurs when the size of the library does not change but book(s) details do. Especially when <see cref="UserDefinedItem.Tags"/>, <see cref="UserDefinedItem.BookStatus"/>, or <see cref="UserDefinedItem.PdfStatus"/> changed values are successfully persisted.
         /// </summary>
-        public static event EventHandler<IEnumerable<LibraryBook>> BookUserDefinedItemCommitted;
+        public static event EventHandler<IEnumerable<LibraryBook>>? BookUserDefinedItemCommitted;
 
         #region Update book details
         public static int UpdateUserDefinedItem(
             this LibraryBook lb,
-            string tags = null,
+            string? tags = null,
             LiberatedStatus? bookStatus = null,
             LiberatedStatus? pdfStatus = null,
-            Rating rating = null)
+            Rating? rating = null)
             => new[] { lb }.UpdateUserDefinedItem(tags, bookStatus, pdfStatus, rating);
 
         public static int UpdateUserDefinedItem(
             this IEnumerable<LibraryBook> lb,
-            string tags = null,
+            string? tags = null,
             LiberatedStatus? bookStatus = null,
             LiberatedStatus? pdfStatus = null,
-            Rating rating = null)
+            Rating? rating = null)
             => updateUserDefinedItem(
                 lb,
                 udi => {
@@ -532,7 +533,8 @@ namespace ApplicationServices
 					var udiEntity = context.Entry(book.Book.UserDefinedItem);
 
 					udiEntity.State = Microsoft.EntityFrameworkCore.EntityState.Modified;
-					udiEntity.Reference(udi => udi.Rating).TargetEntry.State = Microsoft.EntityFrameworkCore.EntityState.Modified;
+                    if (udiEntity.Reference(udi => udi.Rating).TargetEntry is Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry<Rating> ratingEntry)
+                        ratingEntry.State = Microsoft.EntityFrameworkCore.EntityState.Modified;
 				}
 
                 var qtyChanges = context.SaveChanges();
@@ -598,7 +600,8 @@ namespace ApplicationServices
                 return sb.ToString();
 			}
 		}
-        public static LibraryStats GetCounts(IEnumerable<LibraryBook> libraryBooks = null)
+
+        public static LibraryStats GetCounts(IEnumerable<LibraryBook>? libraryBooks = null)
         {
             libraryBooks ??= DbContexts.GetLibrary_Flat_NoTracking();
 

Source/LibationAvalonia/App.axaml

@@ -17,6 +17,9 @@
 				<Setter Property="Foreground" Value="{DynamicResource TextControlForeground}" />
 				<Setter Property="Background" Value="Transparent" />
 			</ControlTheme>
+			<ControlTheme x:Key="{x:Type DataGridCell}" TargetType="DataGridCell" BasedOn="{StaticResource {x:Type DataGridCell}}">
+				<Setter Property="Foreground" Value="{DynamicResource TextControlForeground}" />
+			</ControlTheme>
 			<ResourceDictionary.ThemeDictionaries>
 				<ResourceDictionary x:Key="Light">
 					<SolidColorBrush x:Key="SeriesEntryGridBackgroundBrush" Opacity="0.3" Color="#abffab" />

Source/LibationAvalonia/AvaloniaUtils.cs

@@ -6,6 +6,7 @@ using LibationAvalonia.Dialogs;
 using LibationFileManager;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia
 {
 	internal static class AvaloniaUtils
@@ -14,18 +15,18 @@ namespace LibationAvalonia
 			=> GetBrushFromResources(name, Brushes.Transparent);
 		public static IBrush GetBrushFromResources(string name, IBrush defaultBrush)
 		{
-			if (App.Current.TryGetResource(name, App.Current.ActualThemeVariant, out var value) && value is IBrush brush)
+			if ((App.Current?.TryGetResource(name, App.Current.ActualThemeVariant, out var value) ?? false) && value is IBrush brush)
 				return brush;
 			return defaultBrush;
 		}
 
-		public static Task<DialogResult> ShowDialogAsync(this DialogWindow dialogWindow, Window owner = null)
+		public static Task<DialogResult> ShowDialogAsync(this DialogWindow dialogWindow, Window? owner = null)
 			=> dialogWindow.ShowDialog<DialogResult>(owner ?? App.MainWindow);
 
-		public static Window GetParentWindow(this Control control) => control.GetVisualRoot() as Window;
+		public static Window? GetParentWindow(this Control control) => control.GetVisualRoot() as Window;
 
 
-		private static Bitmap defaultImage;
+		private static Bitmap? defaultImage;
 		public static Bitmap TryLoadImageOrDefault(byte[] picture, PictureSize defaultSize = PictureSize.Native)
 		{
 			try

Source/LibationAvalonia/Dialogs/DialogWindow.cs

@@ -1,6 +1,7 @@
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
+using Avalonia.Styling;
 using LibationFileManager;
 using System;
 using System.Threading.Tasks;
@@ -30,6 +31,9 @@ namespace LibationAvalonia.Dialogs
 			Closing += DialogWindow_Closing;
 
 			UseCustomTitleBar = Configuration.IsWindows;
+
+			if (Design.IsDesignMode)
+				RequestedThemeVariant = ThemeVariant.Dark;
 		}
 
 		private bool fixedMinHeight = false;

Source/LibationAvalonia/Dialogs/EditQuickFilters.axaml.cs

@@ -42,6 +42,17 @@ namespace LibationAvalonia.Dialogs
 		public EditQuickFilters()
 		{
 			InitializeComponent();
+			if (Design.IsDesignMode)
+			{
+				Filters = new ObservableCollection<Filter>([
+					new Filter { Name = "Filter 1", FilterString = "[filter1 string]" },
+					new Filter { Name = "Filter 2", FilterString = "[filter2 string]" },
+					new Filter { Name = "Filter 3", FilterString = "[filter3 string]" },
+					new Filter { Name = "Filter 4", FilterString = "[filter4 string]" }
+					]);
+				DataContext = this;
+				return;
+			}
 
 			// WARNING: accounts persister will write ANY EDIT to object immediately to file
 			// here: copy strings and dispose of persister

Source/LibationAvalonia/Dialogs/EditTemplateDialog.axaml

@@ -51,7 +51,7 @@
 						<DataGridTemplateColumn Width="Auto" Header="Tag">
 							<DataGridTemplateColumn.CellTemplate>
 								<DataTemplate>
-									<TextPresenter Height="18" Margin="10,0,10,0" VerticalAlignment="Center" Text="{Binding Item1}" />
+									<TextBlock Height="18" Margin="10,0,10,0" VerticalAlignment="Center" Text="{Binding Item1}" />
 								</DataTemplate>
 							</DataGridTemplateColumn.CellTemplate>
 						</DataGridTemplateColumn>
@@ -59,7 +59,7 @@
 						<DataGridTemplateColumn Width="Auto" Header="Description">
 							<DataGridTemplateColumn.CellTemplate>
 								<DataTemplate>
-									<TextPresenter
+									<TextBlock
 										Height="18"
 										Margin="10,0,10,0"
 										VerticalAlignment="Center" Text="{Binding Item2}" />

Source/LibationAvalonia/Dialogs/EditTemplateDialog.axaml.cs

@@ -1,8 +1,8 @@
 using Avalonia.Collections;
 using Avalonia.Controls;
 using Avalonia.Controls.Documents;
-using Avalonia.Markup.Xaml;
 using Avalonia.Media;
+using Avalonia.Styling;
 using Dinah.Core;
 using LibationFileManager;
 using ReactiveUI;
@@ -11,175 +11,175 @@ using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
 
-namespace LibationAvalonia.Dialogs
+namespace LibationAvalonia.Dialogs;
+
+public partial class EditTemplateDialog : DialogWindow
 {
-	public partial class EditTemplateDialog : DialogWindow
+	private EditTemplateViewModel _viewModel;
+
+	public EditTemplateDialog()
 	{
-		private EditTemplateViewModel _viewModel;
+		InitializeComponent();
 
-		public EditTemplateDialog()
+		if (Design.IsDesignMode)
 		{
-			InitializeComponent();
+			_ = Configuration.Instance.LibationFiles;
-
+			RequestedThemeVariant  = ThemeVariant.Dark;
-			if (Design.IsDesignMode)
+			var editor = TemplateEditor<Templates.FileTemplate>.CreateFilenameEditor(Configuration.Instance.Books, Configuration.Instance.FileTemplate);
-			{
+			_viewModel = new(Configuration.Instance, editor);
-				_ = Configuration.Instance.LibationFiles;
+			_viewModel.ResetTextBox(editor.EditingTemplate.TemplateText);
-				var editor = TemplateEditor<Templates.FileTemplate>.CreateFilenameEditor(Configuration.Instance.Books, Configuration.Instance.FileTemplate);
+			Title = $"Edit {editor.TemplateName}";
-				_viewModel = new(Configuration.Instance, editor);
-				_viewModel.ResetTextBox(editor.EditingTemplate.TemplateText);
-				Title = $"Edit {editor.TemplateName}";
-				DataContext = _viewModel;
-			}
-		}
-
-		public EditTemplateDialog(ITemplateEditor templateEditor) : this()
-		{
-			ArgumentValidator.EnsureNotNull(templateEditor, nameof(templateEditor));
-
-			_viewModel = new EditTemplateViewModel(Configuration.Instance, templateEditor);
-			_viewModel.ResetTextBox(templateEditor.EditingTemplate.TemplateText);
-			Title = $"Edit {templateEditor.TemplateName}";
 			DataContext = _viewModel;
 		}
+	}
+
+	public EditTemplateDialog(ITemplateEditor templateEditor) : this()
+	{
+		ArgumentValidator.EnsureNotNull(templateEditor, nameof(templateEditor));
+
+		_viewModel = new EditTemplateViewModel(Configuration.Instance, templateEditor);
+		_viewModel.ResetTextBox(templateEditor.EditingTemplate.TemplateText);
+		Title = $"Edit {templateEditor.TemplateName}";
+		DataContext = _viewModel;
+	}
 
 
-		public void EditTemplateViewModel_DoubleTapped(object sender, Avalonia.Input.TappedEventArgs e)
+	public void EditTemplateViewModel_DoubleTapped(object sender, Avalonia.Input.TappedEventArgs e)
+	{
+		var dataGrid = sender as DataGrid;
+
+		var item = (dataGrid.SelectedItem as Tuple<string, string, string>).Item3;
+		if (string.IsNullOrWhiteSpace(item)) return;
+
+		var text = userEditTbox.Text;
+
+		userEditTbox.Text = text.Insert(Math.Min(Math.Max(0, userEditTbox.CaretIndex), text.Length), item);
+		userEditTbox.CaretIndex += item.Length;
+	}
+
+	protected override async Task SaveAndCloseAsync()
+	{
+		if (!await _viewModel.Validate())
+			return;
+
+		await base.SaveAndCloseAsync();
+	}
+
+	public async void SaveButton_Click(object sender, Avalonia.Interactivity.RoutedEventArgs e)
+		=> await SaveAndCloseAsync();
+
+	private class EditTemplateViewModel : ViewModels.ViewModelBase
+	{
+		private readonly Configuration config;
+		public InlineCollection Inlines { get; } = new();
+		public ITemplateEditor TemplateEditor { get; }
+		public EditTemplateViewModel(Configuration configuration, ITemplateEditor templates)
 		{
-			var dataGrid = sender as DataGrid;
+			config = configuration;
+			TemplateEditor = templates;
+			Description = templates.TemplateDescription;
+			ListItems
+			= new AvaloniaList<Tuple<string, string, string>>(
+				TemplateEditor
+				.EditingTemplate
+				.TagsRegistered
+				.Cast<TemplateTags>()
+				.Select(
+					t => new Tuple<string, string, string>(
+						$"<{t.TagName}>",
+						t.Description,
+						t.DefaultValue)
+					)
+				);
 
-			var item = (dataGrid.SelectedItem as Tuple<string, string, string>).Item3;
-			if (string.IsNullOrWhiteSpace(item)) return;
-
-			var text = userEditTbox.Text;
-
-			userEditTbox.Text = text.Insert(Math.Min(Math.Max(0, userEditTbox.CaretIndex), text.Length), item);
-			userEditTbox.CaretIndex += item.Length;
 		}
 
-		protected override async Task SaveAndCloseAsync()
+		// hold the work-in-progress value. not guaranteed to be valid
+		private string _userTemplateText;
+		public string UserTemplateText
 		{
-			if (!await _viewModel.Validate())
+			get => _userTemplateText;
-				return;
+			set
-
-			await base.SaveAndCloseAsync();
-		}
-
-		public async void SaveButton_Click(object sender, Avalonia.Interactivity.RoutedEventArgs e)
-			=> await SaveAndCloseAsync();
-
-		private class EditTemplateViewModel : ViewModels.ViewModelBase
-		{
-			private readonly Configuration config;
-			public InlineCollection Inlines { get; } = new();
-			public ITemplateEditor TemplateEditor { get; }
-			public EditTemplateViewModel(Configuration configuration, ITemplateEditor templates)
 			{
-				config = configuration;
+				this.RaiseAndSetIfChanged(ref _userTemplateText, value);
-				TemplateEditor = templates;
+				templateTb_TextChanged();
-				Description = templates.TemplateDescription;
+			}
-				ListItems
+		}
-				= new AvaloniaList<Tuple<string, string, string>>(
+
+		private string _warningText;
+		public string WarningText { get => _warningText; set => this.RaiseAndSetIfChanged(ref _warningText, value); }
+
+		public string Description { get; }
+
+		public AvaloniaList<Tuple<string, string, string>> ListItems { get; set; }
+
+		public void ResetTextBox(string value) => UserTemplateText = value;
+		public void ResetToDefault() => ResetTextBox(TemplateEditor.DefaultTemplate);
+
+		public async Task<bool> Validate()
+		{
+			if (TemplateEditor.EditingTemplate.IsValid)
+				return true;
+
+			var errors
+				= TemplateEditor
+					.EditingTemplate
+					.Errors
+					.Select(err => $"- {err}")
+					.Aggregate((a, b) => $"{a}\r\n{b}");
+			await MessageBox.Show($"This template text is not valid. Errors:\r\n{errors}", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Error);
+			return false;
+		}
+
+		private void templateTb_TextChanged()
+		{
+			TemplateEditor.SetTemplateText(UserTemplateText);
+
+			const char ZERO_WIDTH_SPACE = '\u200B';
+			var sing = $"{Path.DirectorySeparatorChar}";
+
+			// result: can wrap long paths. eg:
+			// |-- LINE WRAP BOUNDARIES --|
+			// \books\author with a very     <= normal line break on space between words
+			// long name\narrator narrator   
+			// \title                        <= line break on the zero-with space we added before slashes
+			string slashWrap(string val) => val.Replace(sing, $"{ZERO_WIDTH_SPACE}{sing}");
+
+			WarningText
+				= !TemplateEditor.EditingTemplate.HasWarnings
+				? ""
+				: "Warning:\r\n" +
 					TemplateEditor
 					.EditingTemplate
-					.TagsRegistered
+					.Warnings
-					.Cast<TemplateTags>()
+					.Select(err => $"- {err}")
-					.Select(
+					.Aggregate((a, b) => $"{a}\r\n{b}");
-						t => new Tuple<string, string, string>(
-							$"<{t.TagName}>",
-							t.Description,
-							t.DefaultValue)
-						)
-					);
 
-			}
+			var bold = FontWeight.Bold;
+			var reg = FontWeight.Normal;
 
-			// hold the work-in-progress value. not guaranteed to be valid
+			Inlines.Clear();
-			private string _userTemplateText;
+
-			public string UserTemplateText
+			if (!TemplateEditor.IsFilePath)
 			{
-				get => _userTemplateText;
+				Inlines.Add(new Run(TemplateEditor.GetName()) { FontWeight = bold });
-				set
+				return;
-				{
-					this.RaiseAndSetIfChanged(ref _userTemplateText, value);
-					templateTb_TextChanged();
-				}
 			}
 
-			private string _warningText;
+			var folder = TemplateEditor.GetFolderName();
-			public string WarningText { get => _warningText; set => this.RaiseAndSetIfChanged(ref _warningText, value); }
+			var file = TemplateEditor.GetFileName();
+			var ext = config.DecryptToLossy ? "mp3" : "m4b";
 
-			public string Description { get; }
+			Inlines.Add(new Run(slashWrap(TemplateEditor.BaseDirectory.PathWithoutPrefix)) { FontWeight = reg });
+			Inlines.Add(new Run(sing) { FontWeight = reg });
 
-			public AvaloniaList<Tuple<string, string, string>> ListItems { get; set; }
+			Inlines.Add(new Run(slashWrap(folder)) { FontWeight = TemplateEditor.IsFolder ? bold : reg });
 
-			public void ResetTextBox(string value) => UserTemplateText = value;
+			Inlines.Add(new Run(sing));
-			public void ResetToDefault() => ResetTextBox(TemplateEditor.DefaultTemplate);
 
-			public async Task<bool> Validate()
+			Inlines.Add(new Run(slashWrap(file)) { FontWeight = TemplateEditor.IsFolder ? reg : bold });
-			{
-				if (TemplateEditor.EditingTemplate.IsValid)
-					return true;
 
-				var errors
+			Inlines.Add(new Run($".{ext}"));
-					= TemplateEditor
-						.EditingTemplate
-						.Errors
-						.Select(err => $"- {err}")
-						.Aggregate((a, b) => $"{a}\r\n{b}");
-				await MessageBox.Show($"This template text is not valid. Errors:\r\n{errors}", "Invalid", MessageBoxButtons.OK, MessageBoxIcon.Error);
-				return false;
-			}
-
-			private void templateTb_TextChanged()
-			{
-				TemplateEditor.SetTemplateText(UserTemplateText);
-
-				const char ZERO_WIDTH_SPACE = '\u200B';
-				var sing = $"{Path.DirectorySeparatorChar}";
-
-				// result: can wrap long paths. eg:
-				// |-- LINE WRAP BOUNDARIES --|
-				// \books\author with a very     <= normal line break on space between words
-				// long name\narrator narrator   
-				// \title                        <= line break on the zero-with space we added before slashes
-				string slashWrap(string val) => val.Replace(sing, $"{ZERO_WIDTH_SPACE}{sing}");
-
-				WarningText
-					= !TemplateEditor.EditingTemplate.HasWarnings
-					? ""
-					: "Warning:\r\n" +
-						TemplateEditor
-						.EditingTemplate
-						.Warnings
-						.Select(err => $"- {err}")
-						.Aggregate((a, b) => $"{a}\r\n{b}");
-
-				var bold = FontWeight.Bold;
-				var reg = FontWeight.Normal;
-
-				Inlines.Clear();
-
-				if (!TemplateEditor.IsFilePath)
-				{
-					Inlines.Add(new Run(TemplateEditor.GetName()) { FontWeight = bold });
-					return;
-				}
-
-				var folder = TemplateEditor.GetFolderName();
-				var file = TemplateEditor.GetFileName();
-				var ext = config.DecryptToLossy ? "mp3" : "m4b";
-
-				Inlines.Add(new Run(slashWrap(TemplateEditor.BaseDirectory.PathWithoutPrefix)) { FontWeight = reg });
-				Inlines.Add(new Run(sing) { FontWeight = reg });
-
-				Inlines.Add(new Run(slashWrap(folder)) { FontWeight = TemplateEditor.IsFolder ? bold : reg });
-
-				Inlines.Add(new Run(sing));
-
-				Inlines.Add(new Run(slashWrap(file)) { FontWeight = TemplateEditor.IsFolder ? reg : bold });
-
-				Inlines.Add(new Run($".{ext}"));
-			}
 		}
 	}
 }

Source/LibationAvalonia/FormSaveExtension.cs

@@ -6,17 +6,17 @@ using LibationFileManager;
 using System;
 using System.Linq;
 
+#nullable enable
 namespace LibationAvalonia
 {
 	public static class FormSaveExtension
 	{
-		static readonly WindowIcon WindowIcon;
+		static readonly WindowIcon? WindowIcon;
 		static FormSaveExtension()
 		{
-			if (Application.Current.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop && desktop.MainWindow is not null)
+			WindowIcon = Application.Current?.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop && desktop.MainWindow?.Icon is WindowIcon icon
-				WindowIcon = desktop.MainWindow.Icon;
+				? icon
-			else
+				: null;
-				WindowIcon = null;
 		}
 
 		public static void SetLibationIcon(this Window form)
@@ -29,7 +29,7 @@ namespace LibationAvalonia
 			if (Design.IsDesignMode) return;
 			try
 			{
-				var savedState = config.GetNonString<FormSizeAndPosition>(defaultValue: null, form.GetType().Name);
+				var savedState = config.GetNonString<FormSizeAndPosition?>(defaultValue: null, form.GetType().Name);
 
 				if (savedState is null)
 					return;
@@ -40,12 +40,14 @@ namespace LibationAvalonia
 					savedState.Width = (int)form.Width;
 					savedState.Height = (int)form.Height;
 				}
-
+				if (form.Screens.Primary is Screen primaryScreen)
-				// Fit to the current screen size in case the screen resolution changed since the size was last persisted
+				{
-				if (savedState.Width > form.Screens.Primary.WorkingArea.Width)
+					// Fit to the current screen size in case the screen resolution changed since the size was last persisted
-					savedState.Width = form.Screens.Primary.WorkingArea.Width;
+					if (savedState.Width > primaryScreen.WorkingArea.Width)
-				if (savedState.Height > form.Screens.Primary.WorkingArea.Height)
+						savedState.Width = primaryScreen.WorkingArea.Width;
-					savedState.Height = form.Screens.Primary.WorkingArea.Height;
+					if (savedState.Height > primaryScreen.WorkingArea.Height)
+						savedState.Height = primaryScreen.WorkingArea.Height;
+				}
 
 				var rect = new PixelRect(savedState.X, savedState.Y, savedState.Width, savedState.Height);
 

Source/LibationAvalonia/Program.cs

@@ -5,10 +5,10 @@ using System.Threading.Tasks;
 using ApplicationServices;
 using AppScaffolding;
 using Avalonia;
-using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.ReactiveUI;
 using LibationFileManager;
 
+#nullable enable
 namespace LibationAvalonia
 {
 	static class Program
@@ -57,7 +57,7 @@ namespace LibationAvalonia
 					App.LibraryTask = Task.Run(() => DbContexts.GetLibrary_Flat_NoTracking(includeParents: true));
 				}
 
-				BuildAvaloniaApp().StartWithClassicDesktopLifetime(null);
+				BuildAvaloniaApp().StartWithClassicDesktopLifetime([]);
 			}
 			catch (Exception ex)
 			{
@@ -77,27 +77,27 @@ namespace LibationAvalonia
 		private static void LogError(object exceptionObject)
 		{
 			var logError = $"""
-				{DateTime.Now} - Libation Crash
+			{DateTime.Now} - Libation Crash
-				 OS                    {Configuration.OS}
+			 OS                    {Configuration.OS}
-				 Version               {LibationScaffolding.BuildVersion}
+			 Version               {LibationScaffolding.BuildVersion}
-				 ReleaseIdentifier     {LibationScaffolding.ReleaseIdentifier}
+			 ReleaseIdentifier     {LibationScaffolding.ReleaseIdentifier}
-				 InteropFunctionsType  {InteropFactory.InteropFunctionsType}
+			 InteropFunctionsType  {InteropFactory.InteropFunctionsType}
-				 LibationFiles         {getConfigValue(c => c.LibationFiles)}
+			 LibationFiles         {getConfigValue(c => c.LibationFiles)}
-				 Books Folder          {getConfigValue(c => c.Books)}
+			 Books Folder          {getConfigValue(c => c.Books)}
-				 === EXCEPTION ===
+			 === EXCEPTION ===
-				 {exceptionObject}
+			 {exceptionObject}
-				""";
+			""";
 
 			var crashLog = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "LibationCrash.log");
 
 			using var sw = new StreamWriter(crashLog, true);
 			sw.WriteLine(logError);
 
-			static string getConfigValue(Func<Configuration, string> selector)
+			static string getConfigValue(Func<Configuration, string?> selector)
 			{
 				try
 				{
-					return selector(Configuration.Instance);
+					return selector(Configuration.Instance) ?? "[null]";
 				}
 				catch (Exception ex)
 				{

Source/LibationAvalonia/ViewModels/AvaloniaEntryStatus.cs

@@ -4,6 +4,7 @@ using DataLayer;
 using LibationUiBase.GridView;
 using System;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	public class AvaloniaEntryStatus : EntryStatus, IEntryStatus, IComparable
@@ -17,6 +18,6 @@ namespace LibationAvalonia.ViewModels
 			=> AvaloniaUtils.TryLoadImageOrDefault(picture, LibationFileManager.PictureSize._80x80);
 
 		//Button icons are handled by LiberateStatusButton
-		protected override Bitmap GetResourceImage(string rescName) => null;
+		protected override Bitmap? GetResourceImage(string rescName) => null;
 	}
 }

Source/LibationAvalonia/ViewModels/LiberateStatusButtonViewModel.cs

@@ -1,5 +1,6 @@
 using ReactiveUI;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	public class LiberateStatusButtonViewModel : ViewModelBase

Source/LibationAvalonia/ViewModels/MainVM.BackupCounts.cs

@@ -6,12 +6,13 @@ using ReactiveUI;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM
 	{
-		private Task<LibraryCommands.LibraryStats> updateCountsTask;
+		private Task<LibraryCommands.LibraryStats>? updateCountsTask;
-		private LibraryCommands.LibraryStats _libraryStats;
+		private LibraryCommands.LibraryStats? _libraryStats;
 
 		/// <summary> The "Begin Book and PDF Backup" menu item header text </summary>
 		public string BookBackupsToolStripText { get; private set; } = "Begin Book and PDF Backups: 0";
@@ -19,7 +20,7 @@ namespace LibationAvalonia.ViewModels
 		public string PdfBackupsToolStripText { get; private set; } = "Begin PDF Only Backups: 0";
 
 		/// <summary> The user's library statistics </summary>
-		public LibraryCommands.LibraryStats LibraryStats
+		public LibraryCommands.LibraryStats? LibraryStats
 		{
 			get => _libraryStats;
 			set
@@ -27,12 +28,12 @@ namespace LibationAvalonia.ViewModels
 				this.RaiseAndSetIfChanged(ref _libraryStats, value);
 
 				BookBackupsToolStripText
-					= LibraryStats.HasPendingBooks
+					= LibraryStats?.HasPendingBooks ?? false
 					? "Begin " + menufyText($"Book and PDF Backups: {LibraryStats.PendingBooks} remaining")
 					: "All books have been liberated";
 
 				PdfBackupsToolStripText
-					= LibraryStats.pdfsNotDownloaded > 0
+					= LibraryStats?.pdfsNotDownloaded > 0
 					? "Begin " + menufyText($"PDF Only Backups: {LibraryStats.pdfsNotDownloaded} remaining")
 					: "All PDFs have been downloaded";
 
@@ -48,7 +49,7 @@ namespace LibationAvalonia.ViewModels
 				=> await SetBackupCountsAsync(null);
 		}
 
-		public async Task SetBackupCountsAsync(IEnumerable<LibraryBook> libraryBooks)
+		public async Task SetBackupCountsAsync(IEnumerable<LibraryBook>? libraryBooks)
 		{
 			if (updateCountsTask?.IsCompleted ?? true)
 			{

Source/LibationAvalonia/ViewModels/MainVM.Export.cs

@@ -5,6 +5,7 @@ using LibationFileManager;
 using System;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM
@@ -18,7 +19,7 @@ namespace LibationAvalonia.ViewModels
 				var options = new FilePickerSaveOptions
 				{
 					Title = "Where to export Library",
-					SuggestedStartLocation = await MainWindow.StorageProvider.TryGetFolderFromPathAsync(Configuration.Instance.Books.PathWithoutPrefix),
+					SuggestedStartLocation = await MainWindow.StorageProvider.TryGetFolderFromPathAsync(Configuration.Instance.Books?.PathWithoutPrefix ?? Configuration.DefaultBooksDirectory),
 					SuggestedFileName = $"Libation Library Export {DateTime.Now:yyyy-MM-dd}",
 					DefaultExtension = "xlsx",
 					ShowOverwritePrompt = true,
@@ -41,7 +42,7 @@ namespace LibationAvalonia.ViewModels
 							AppleUniformTypeIdentifiers = new[] { "public.json" }
 						},
 						new("All files (*.*)") { Patterns = new[] { "*" } }
-					}
+						}
 				};
 
 				var selectedFile = (await MainWindow.StorageProvider.SaveFilePickerAsync(options))?.TryGetLocalPath();

Source/LibationAvalonia/ViewModels/MainVM.Filters.cs

@@ -9,16 +9,17 @@ using System;
 using System.Linq;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM
 	{
-		private QuickFilters.NamedFilter lastGoodFilter = new(string.Empty, null);
+		private QuickFilters.NamedFilter? lastGoodFilter = new(string.Empty, null);
-		private QuickFilters.NamedFilter _selectedNamedFilter = new(string.Empty, null);
+		private QuickFilters.NamedFilter? _selectedNamedFilter = new(string.Empty, null);
 		private bool _firstFilterIsDefault = true;
 
 		/// <summary> Library filterting query </summary>
-		public QuickFilters.NamedFilter SelectedNamedFilter { get => _selectedNamedFilter; set => this.RaiseAndSetIfChanged(ref _selectedNamedFilter, value); }
+		public QuickFilters.NamedFilter? SelectedNamedFilter { get => _selectedNamedFilter; set => this.RaiseAndSetIfChanged(ref _selectedNamedFilter, value); }
 		public AvaloniaList<Control> QuickFilterMenuItems { get; } = new();
 		/// <summary> Indicates if the first quick filter is the default filter </summary>
 		public bool FirstFilterIsDefault { get => _firstFilterIsDefault; set => QuickFilters.UseDefault = this.RaiseAndSetIfChanged(ref _firstFilterIsDefault, value); }
@@ -50,36 +51,44 @@ namespace LibationAvalonia.ViewModels
 			QuickFilterMenuItems.Add(new Separator());
 		}
 
-		public void AddQuickFilterBtn() => QuickFilters.Add(SelectedNamedFilter);
+		public void AddQuickFilterBtn() { if (SelectedNamedFilter != null) QuickFilters.Add(SelectedNamedFilter); }
 		public async Task FilterBtn() => await PerformFilter(SelectedNamedFilter);
 		public async Task FilterHelpBtn() => await new LibationAvalonia.Dialogs.SearchSyntaxDialog().ShowDialog(MainWindow);
 		public void ToggleFirstFilterIsDefault() => FirstFilterIsDefault = !FirstFilterIsDefault;
 		public async Task EditQuickFiltersAsync() => await new LibationAvalonia.Dialogs.EditQuickFilters().ShowDialog(MainWindow);
-		public async Task PerformFilter(QuickFilters.NamedFilter namedFilter)
+		public async Task PerformFilter(QuickFilters.NamedFilter? namedFilter)
 		{
 			SelectedNamedFilter = namedFilter;
+			var tryFilter = namedFilter?.Filter;
 
 			try
 			{
-				await ProductsDisplay.Filter(namedFilter.Filter);
+				await ProductsDisplay.Filter(tryFilter);
 				lastGoodFilter = namedFilter;
 			}
 			catch (Exception ex)
 			{
-				await MessageBox.Show($"Bad filter string:\r\n\r\n{ex.Message}", "Bad filter string", MessageBoxButtons.OK, MessageBoxIcon.Error);
+				Serilog.Log.Logger.Error(ex, "Error performing filtering. {@namedFilter} {@lastGoodFilter}", namedFilter, lastGoodFilter);
+				await MessageBox.Show($"Bad filter string: \"{tryFilter}\"\r\n\r\n{ex.Message}", "Bad filter string", MessageBoxButtons.OK, MessageBoxIcon.Error);
 
 				// re-apply last good filter
 				await PerformFilter(lastGoodFilter);
 			}
 		}
 
-		private void updateFiltersMenu(object _ = null, object __ = null)
+		private void updateFiltersMenu(object? _ = null, object? __ = null)
 		{
-			//Clear all filters
+			if (NativeMenu.GetMenu(MainWindow)?.Items[3] is not NativeMenuItem ss ||
-			var quickFilterNativeMenu = (NativeMenuItem)NativeMenu.GetMenu(MainWindow).Items[3];
+				ss.Menu is not NativeMenu quickFilterNativeMenu)
-			for (int i = quickFilterNativeMenu.Menu.Items.Count - 1; i >= 3; i--)
 			{
-				var command = ((NativeMenuItem)quickFilterNativeMenu.Menu.Items[i]).Command as IDisposable;
+				Serilog.Log.Logger.Error($"Unable to find {nameof(quickFilterNativeMenu)}");
+				return;
+			}
+
+			//Clear all filters
+			for (int i = quickFilterNativeMenu.Items.Count - 1; i >= 3; i--)
+			{
+				var command = ((NativeMenuItem)quickFilterNativeMenu.Items[i]).Command as IDisposable;
 				if (command != null)
 				{
 					var existingBinding = MainWindow.KeyBindings.FirstOrDefault(kb => kb.Command == command);
@@ -89,7 +98,7 @@ namespace LibationAvalonia.ViewModels
 					command.Dispose();
 				}
 
-				quickFilterNativeMenu.Menu.Items.RemoveAt(i);
+				quickFilterNativeMenu.Items.RemoveAt(i);
 				QuickFilterMenuItems.RemoveAt(i);
 			}
 
@@ -116,7 +125,7 @@ namespace LibationAvalonia.ViewModels
 				}
 
 				QuickFilterMenuItems.Add(menuItem);
-				quickFilterNativeMenu.Menu.Items.Add(nativeMenuItem);
+				quickFilterNativeMenu.Items.Add(nativeMenuItem);
 			}
 		}
 	}

Source/LibationAvalonia/ViewModels/MainVM.Import.cs

@@ -8,6 +8,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using Avalonia.Input;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	public partial class MainVM
@@ -90,7 +91,9 @@ namespace LibationAvalonia.ViewModels
 		public async Task ScanAccountAsync()
 		{
 			using var persister = AudibleApiStorage.GetAccountsSettingsPersister();
-			await scanLibrariesAsync(persister.AccountsSettings.GetAll().FirstOrDefault());
+			var firstAccount = persister.AccountsSettings.GetAll().FirstOrDefault();
+			if (firstAccount != null)
+				await scanLibrariesAsync(firstAccount);
 		}
 
 		public async Task ScanAllAccountsAsync()
@@ -194,7 +197,7 @@ namespace LibationAvalonia.ViewModels
 			await ProductsDisplay.ScanAndRemoveBooksAsync(accounts);
 		}
 
-		private async Task scanLibrariesAsync(params Account[] accounts)
+		private async Task scanLibrariesAsync(params Account[]? accounts)
 		{
 			try
 			{
@@ -218,37 +221,44 @@ namespace LibationAvalonia.ViewModels
 			}
 		}
 
-		private void refreshImportMenu(object _ = null, EventArgs __ = null)
+		private void refreshImportMenu(object? _ = null, EventArgs? __ = null)
 		{
 			using var persister = AudibleApiStorage.GetAccountsSettingsPersister();
 			AccountsCount = persister.AccountsSettings.Accounts.Count;
 
-			var importMenuItem = (NativeMenuItem)NativeMenu.GetMenu(MainWindow).Items[0];
 
-			for (int i = importMenuItem.Menu.Items.Count - 1; i >= 2; i--)
+			if (NativeMenu.GetMenu(MainWindow)?.Items[0] is not NativeMenuItem ss ||
-				importMenuItem.Menu.Items.RemoveAt(i);
+				ss.Menu is not NativeMenu importMenuItem)
+			{
+				Serilog.Log.Logger.Error($"Unable to find {nameof(importMenuItem)}");
+				return;
+			}
+
+
+			for (int i = importMenuItem.Items.Count - 1; i >= 2; i--)
+				importMenuItem.Items.RemoveAt(i);
 
 			if (AccountsCount < 1)
 			{
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "No accounts yet. Add Account...", Command = ReactiveCommand.Create(AddAccountsAsync) });
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "No accounts yet. Add Account...", Command = ReactiveCommand.Create(AddAccountsAsync) });
 			}
 			else if (AccountsCount == 1)
 			{
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Scan Library", Command = ReactiveCommand.Create(ScanAccountAsync), Gesture = new KeyGesture(Key.S, KeyModifiers.Alt | KeyModifiers.Meta)});
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "Scan Library", Command = ReactiveCommand.Create(ScanAccountAsync), Gesture = new KeyGesture(Key.S, KeyModifiers.Alt | KeyModifiers.Meta) });
-				importMenuItem.Menu.Items.Add(new NativeMenuItemSeparator());
+				importMenuItem.Items.Add(new NativeMenuItemSeparator());
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Remove Library Books", Command = ReactiveCommand.Create(RemoveBooksAsync), Gesture = new KeyGesture(Key.R, KeyModifiers.Alt | KeyModifiers.Meta)});
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "Remove Library Books", Command = ReactiveCommand.Create(RemoveBooksAsync), Gesture = new KeyGesture(Key.R, KeyModifiers.Alt | KeyModifiers.Meta) });
 			}
 			else
 			{
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Scan Library of All Accounts", Command = ReactiveCommand.Create(ScanAllAccountsAsync), Gesture = new KeyGesture(Key.S, KeyModifiers.Alt | KeyModifiers.Meta)});
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "Scan Library of All Accounts", Command = ReactiveCommand.Create(ScanAllAccountsAsync), Gesture = new KeyGesture(Key.S, KeyModifiers.Alt | KeyModifiers.Meta) });
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Scan Library of Some Accounts", Command = ReactiveCommand.Create(ScanSomeAccountsAsync), Gesture = new KeyGesture(Key.S, KeyModifiers.Alt | KeyModifiers.Meta | KeyModifiers.Shift) });
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "Scan Library of Some Accounts", Command = ReactiveCommand.Create(ScanSomeAccountsAsync), Gesture = new KeyGesture(Key.S, KeyModifiers.Alt | KeyModifiers.Meta | KeyModifiers.Shift) });
-				importMenuItem.Menu.Items.Add(new NativeMenuItemSeparator());
+				importMenuItem.Items.Add(new NativeMenuItemSeparator());
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Remove Books from All Accounts", Command = ReactiveCommand.Create(RemoveBooksAllAsync), Gesture = new KeyGesture(Key.R, KeyModifiers.Alt | KeyModifiers.Meta)});
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "Remove Books from All Accounts", Command = ReactiveCommand.Create(RemoveBooksAllAsync), Gesture = new KeyGesture(Key.R, KeyModifiers.Alt | KeyModifiers.Meta) });
-				importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Remove Books from Some Accounts", Command = ReactiveCommand.Create(RemoveBooksSomeAsync), Gesture = new KeyGesture(Key.R, KeyModifiers.Alt | KeyModifiers.Meta | KeyModifiers.Shift) });
+				importMenuItem.Items.Add(new NativeMenuItem { Header = "Remove Books from Some Accounts", Command = ReactiveCommand.Create(RemoveBooksSomeAsync), Gesture = new KeyGesture(Key.R, KeyModifiers.Alt | KeyModifiers.Meta | KeyModifiers.Shift) });
 			}
 
-			importMenuItem.Menu.Items.Add(new NativeMenuItemSeparator());
+			importMenuItem.Items.Add(new NativeMenuItemSeparator());
-			importMenuItem.Menu.Items.Add(new NativeMenuItem { Header = "Locate Audiobooks...", Command = ReactiveCommand.Create(LocateAudiobooksAsync) });
+			importMenuItem.Items.Add(new NativeMenuItem { Header = "Locate Audiobooks...", Command = ReactiveCommand.Create(LocateAudiobooksAsync) });
 		}
 	}
 }

Source/LibationAvalonia/ViewModels/MainVM.Liberate.cs

@@ -5,6 +5,7 @@ using System.Linq;
 using System.Threading.Tasks;
 using DataLayer;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM

Source/LibationAvalonia/ViewModels/MainVM.ProcessQueue.cs

@@ -6,6 +6,7 @@ using Dinah.Core;
 using LibationUiBase.GridView;
 using ReactiveUI;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM

Source/LibationAvalonia/ViewModels/MainVM.ScanAuto.cs

@@ -6,6 +6,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM
@@ -50,7 +51,7 @@ namespace LibationAvalonia.ViewModels
 		}
 
 
-		private List<(string AccountId, string LocaleName)> preSaveDefaultAccounts;
+		private List<(string AccountId, string LocaleName)>? preSaveDefaultAccounts;
 		private List<(string AccountId, string LocaleName)> getDefaultAccounts()
 		{
 			using var persister = AudibleApiStorage.GetAccountsSettingsPersister();
@@ -61,17 +62,17 @@ namespace LibationAvalonia.ViewModels
 				.ToList();
 		}
 
-		private void accountsPreSave(object sender = null, EventArgs e = null)
+		private void accountsPreSave(object? sender = null, EventArgs? e = null)
 			=> preSaveDefaultAccounts = getDefaultAccounts();
 
-		private void accountsPostSave(object sender = null, EventArgs e = null)
+		private void accountsPostSave(object? sender = null, EventArgs? e = null)
 		{
-			if (getDefaultAccounts().Except(preSaveDefaultAccounts).Any())
+			if (getDefaultAccounts().Except(preSaveDefaultAccounts ?? Enumerable.Empty<(string AccountId, string LocaleName)>()).Any())
 				startAutoScan();
 		}
 
 		[PropertyChangeFilter(nameof(Configuration.AutoScan))]
-		private void startAutoScan(object sender = null, EventArgs e = null)
+		private void startAutoScan(object? sender = null, EventArgs? e = null)
 		{
 			AutoScanChecked = Configuration.Instance.AutoScan;
 			if (AutoScanChecked)

Source/LibationAvalonia/ViewModels/MainVM.Settings.cs

@@ -4,6 +4,7 @@ using ReactiveUI;
 using System;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM
@@ -12,7 +13,9 @@ namespace LibationAvalonia.ViewModels
 		public bool MenuBarVisible { get => _menuBarVisible; set => this.RaiseAndSetIfChanged(ref _menuBarVisible, value); }
 		private void Configure_Settings()
 		{
-			((NativeMenuItem)NativeMenu.GetMenu(App.Current).Items[0]).Command = ReactiveCommand.Create(ShowAboutAsync);
+			if (App.Current is Avalonia.Application app &&
+				NativeMenu.GetMenu(app)?.Items[0] is NativeMenuItem aboutMenu)
+				aboutMenu.Command = ReactiveCommand.Create(ShowAboutAsync);
 		}
 
 		public Task ShowAboutAsync() => new LibationAvalonia.Dialogs.AboutDialog().ShowDialog(MainWindow);

Source/LibationAvalonia/ViewModels/MainVM.VisibleBooks.cs

@@ -6,6 +6,7 @@ using Avalonia.Threading;
 using LibationAvalonia.Dialogs;
 using ReactiveUI;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM
@@ -56,13 +57,13 @@ namespace LibationAvalonia.ViewModels
 			this.RaisePropertyChanged(nameof(LiberateVisibleToolStripText_2));
 		}
 
-		public async void ProductsDisplay_VisibleCountChanged(object sender, int qty)
+		public async void ProductsDisplay_VisibleCountChanged(object? sender, int qty)
 		{
 			setVisibleCount(qty);
 			await Dispatcher.UIThread.InvokeAsync(setLiberatedVisibleMenuItem);
 		}
 
-		private async void setLiberatedVisibleMenuItemAsync(object _, object __)
+		private async void setLiberatedVisibleMenuItemAsync(object? _, object __)
 			=> await Dispatcher.UIThread.InvokeAsync(setLiberatedVisibleMenuItem);
 
 

Source/LibationAvalonia/ViewModels/MainVM._NoUI.cs

@@ -2,6 +2,7 @@
 using LibationUiBase;
 using System.IO;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	partial class MainVM

Source/LibationAvalonia/ViewModels/MainVM.cs

@@ -6,6 +6,7 @@ using ReactiveUI;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	public partial class MainVM : ViewModelBase
@@ -37,11 +38,18 @@ namespace LibationAvalonia.ViewModels
 			Configure_VisibleBooks();
 		}
 
-		private async void LibraryCommands_LibrarySizeChanged(object sender, List<LibraryBook> fullLibrary)
+		private async void LibraryCommands_LibrarySizeChanged(object? sender, List<LibraryBook> fullLibrary)
 		{
-			await Task.WhenAll(
+			try
-				SetBackupCountsAsync(fullLibrary),
+			{
-				Task.Run(() => ProductsDisplay.UpdateGridAsync(fullLibrary)));
+				await Task.WhenAll(
+					SetBackupCountsAsync(fullLibrary),
+					Task.Run(() => ProductsDisplay.UpdateGridAsync(fullLibrary)));
+			}
+			catch (System.Exception ex)
+			{
+				await MessageBox.ShowAdminAlert(MainWindow, "An error occurred while updating the library.", "Library Size Change Error", ex);
+			}
 		}
 
 		private static string menufyText(string header) => Configuration.IsMacOs ? header : $"_{header}";

Source/LibationAvalonia/ViewModels/ProcessBookViewModel.cs

@@ -16,6 +16,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	public enum ProcessBookResult
@@ -45,28 +46,28 @@ namespace LibationAvalonia.ViewModels
 	/// </summary>
 	public class ProcessBookViewModel : ViewModelBase
 	{
-		public event EventHandler Completed;
+		public event EventHandler? Completed;
 
 		public LibraryBook LibraryBook { get; private set; }
 
 		private ProcessBookResult _result = ProcessBookResult.None;
 		private ProcessBookStatus _status = ProcessBookStatus.Queued;
-		private string _narrator;
+		private string? _narrator;
-		private string _author;
+		private string? _author;
-		private string _title;
+		private string? _title;
 		private int _progress;
-		private string _eta;
+		private string? _eta;
-		private Bitmap _cover;
+		private Bitmap? _cover;
 
 		#region Properties exposed to the view
 		public ProcessBookResult Result { get => _result; set { this.RaiseAndSetIfChanged(ref _result, value); this.RaisePropertyChanged(nameof(StatusText)); } }
 		public ProcessBookStatus Status { get => _status; set { this.RaiseAndSetIfChanged(ref _status, value); this.RaisePropertyChanged(nameof(BackgroundColor)); this.RaisePropertyChanged(nameof(IsFinished)); this.RaisePropertyChanged(nameof(IsDownloading)); this.RaisePropertyChanged(nameof(Queued)); } }
-		public string Narrator { get => _narrator; set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _narrator, value)); }
+		public string? Narrator { get => _narrator; set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _narrator, value)); }
-		public string Author { get => _author; set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _author, value)); }
+		public string? Author { get => _author; set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _author, value)); }
-		public string Title { get => _title; set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _title, value)); }
+		public string? Title { get => _title; set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _title, value)); }
 		public int Progress { get => _progress; private set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _progress, value)); }
-		public string ETA { get => _eta; private set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _eta, value)); }
+		public string? ETA { get => _eta; private set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _eta, value)); }
-		public Bitmap Cover { get => _cover; private set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _cover, value)); }
+		public Bitmap? Cover { get => _cover; private set => Dispatcher.UIThread.Invoke(() => this.RaiseAndSetIfChanged(ref _cover, value)); }
 		public bool IsFinished => Status is not ProcessBookStatus.Queued and not ProcessBookStatus.Working;
 		public bool IsDownloading => Status is ProcessBookStatus.Working;
 		public bool Queued => Status is ProcessBookStatus.Queued;
@@ -95,8 +96,8 @@ namespace LibationAvalonia.ViewModels
 
 		private TimeSpan TimeRemaining { set { ETA = $"ETA: {value:mm\\:ss}"; } }
 		private Processable CurrentProcessable => _currentProcessable ??= Processes.Dequeue().Invoke();
-		private Processable NextProcessable() => _currentProcessable = null;
+		private Processable? NextProcessable() => _currentProcessable = null;
-		private Processable _currentProcessable;
+		private Processable? _currentProcessable;
 		private readonly Queue<Func<Processable>> Processes = new();
 		private readonly LogMe Logger;
 
@@ -118,7 +119,7 @@ namespace LibationAvalonia.ViewModels
 			_cover = AvaloniaUtils.TryLoadImageOrDefault(picture, PictureSize._80x80);
 		}
 
-		private void PictureStorage_PictureCached(object sender, PictureCachedEventArgs e)
+		private void PictureStorage_PictureCached(object? sender, PictureCachedEventArgs e)
 		{
 			if (e.Definition.PictureId == LibraryBook.Book.PictureId)
 			{
@@ -255,14 +256,14 @@ namespace LibationAvalonia.ViewModels
 
 		#region AudioDecodable event handlers
 
-		private void AudioDecodable_TitleDiscovered(object sender, string title) => Title = title;
+		private void AudioDecodable_TitleDiscovered(object? sender, string title) => Title = title;
 
-		private void AudioDecodable_AuthorsDiscovered(object sender, string authors) => Author = authors;
+		private void AudioDecodable_AuthorsDiscovered(object? sender, string authors) => Author = authors;
 
-		private void AudioDecodable_NarratorsDiscovered(object sender, string narrators) => Narrator = narrators;
+		private void AudioDecodable_NarratorsDiscovered(object? sender, string narrators) => Narrator = narrators;
 
 
-		private byte[] AudioDecodable_RequestCoverArt(object sender, EventArgs e)
+		private byte[] AudioDecodable_RequestCoverArt(object? sender, EventArgs e)
 		{
 			var quality
 				= Configuration.Instance.FileDownloadQuality == Configuration.DownloadQuality.High && LibraryBook.Book.PictureLarge is not null
@@ -275,7 +276,7 @@ namespace LibationAvalonia.ViewModels
 			return coverData;
 		}
 
-		private void AudioDecodable_CoverImageDiscovered(object sender, byte[] coverArt)
+		private void AudioDecodable_CoverImageDiscovered(object? sender, byte[] coverArt)
 		{
 			using var ms = new System.IO.MemoryStream(coverArt);
 			Cover = new Avalonia.Media.Imaging.Bitmap(ms);
@@ -284,10 +285,10 @@ namespace LibationAvalonia.ViewModels
 		#endregion
 
 		#region Streamable event handlers
-		private void Streamable_StreamingTimeRemaining(object sender, TimeSpan timeRemaining) => TimeRemaining = timeRemaining;
+		private void Streamable_StreamingTimeRemaining(object? sender, TimeSpan timeRemaining) => TimeRemaining = timeRemaining;
 
 
-		private void Streamable_StreamingProgressChanged(object sender, Dinah.Core.Net.Http.DownloadProgress downloadProgress)
+		private void Streamable_StreamingProgressChanged(object? sender, Dinah.Core.Net.Http.DownloadProgress downloadProgress)
 		{
 			if (!downloadProgress.ProgressPercentage.HasValue)
 				return;
@@ -302,21 +303,25 @@ namespace LibationAvalonia.ViewModels
 
 		#region Processable event handlers
 
-		private async void Processable_Begin(object sender, LibraryBook libraryBook)
+		private async void Processable_Begin(object? sender, LibraryBook libraryBook)
 		{
 			await Dispatcher.UIThread.InvokeAsync(() => Status = ProcessBookStatus.Working);
 
-			Logger.Info($"{Environment.NewLine}{((Processable)sender).Name} Step, Begin: {libraryBook.Book}");
+			if (sender is Processable processable)
+				Logger.Info($"{Environment.NewLine}{processable.Name} Step, Begin: {libraryBook.Book}");
 
 			Title = libraryBook.Book.TitleWithSubtitle;
 			Author = libraryBook.Book.AuthorNames();
 			Narrator = libraryBook.Book.NarratorNames();
 		}
 
-		private async void Processable_Completed(object sender, LibraryBook libraryBook)
+		private async void Processable_Completed(object? sender, LibraryBook libraryBook)
 		{
-			Logger.Info($"{((Processable)sender).Name} Step, Completed: {libraryBook.Book}");
+			if (sender is Processable processable)
-			UnlinkProcessable((Processable)sender);
+			{
+				Logger.Info($"{processable.Name} Step, Completed: {libraryBook.Book}");
+				UnlinkProcessable(processable);
+			}
 
 			if (Processes.Count == 0)
 			{
@@ -375,7 +380,7 @@ namespace LibationAvalonia.ViewModels
 					: str;
 
 				details =
-$@"  Title: {libraryBook.Book.TitleWithSubtitle}
+	$@"  Title: {libraryBook.Book.TitleWithSubtitle}
   ID: {libraryBook.Book.AudibleProductId}
   Author: {trunc(libraryBook.Book.AuthorNames())}
   Narr: {trunc(libraryBook.Book.NarratorNames())}";

Source/LibationAvalonia/ViewModels/ProcessQueueViewModel.cs

@@ -12,15 +12,17 @@ using System.Collections.ObjectModel;
 using System.Linq;
 using System.Threading.Tasks;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
+
 	public class ProcessQueueViewModel : ViewModelBase, ILogForm
 	{
 		public ObservableCollection<LogEntry> LogEntries { get; } = new();
 		public AvaloniaList<ProcessBookViewModel> Items { get; } = new();
 		public TrackedQueue<ProcessBookViewModel> Queue { get; }
-		public ProcessBookViewModel SelectedItem { get; set; }
+		public ProcessBookViewModel? SelectedItem { get; set; }
-		public Task QueueRunner { get; private set; }
+		public Task? QueueRunner { get; private set; }
 		public bool Running => !QueueRunner?.IsCompleted ?? false;
 
 		private readonly LogMe Logger;
@@ -41,14 +43,14 @@ namespace LibationAvalonia.ViewModels
 		private int _completedCount;
 		private int _errorCount;
 		private int _queuedCount;
-		private string _runningTime;
+		private string? _runningTime;
 		private bool _progressBarVisible;
 		private decimal _speedLimit;
 
 		public int CompletedCount { get => _completedCount; private set => Dispatcher.UIThread.Invoke(() => { this.RaiseAndSetIfChanged(ref _completedCount, value); this.RaisePropertyChanged(nameof(AnyCompleted)); }); }
 		public int QueuedCount { get => _queuedCount; private set => Dispatcher.UIThread.Invoke(() => { this.RaiseAndSetIfChanged(ref _queuedCount, value); this.RaisePropertyChanged(nameof(AnyQueued)); }); }
 		public int ErrorCount { get => _errorCount; private set => Dispatcher.UIThread.Invoke(() => { this.RaiseAndSetIfChanged(ref _errorCount, value); this.RaisePropertyChanged(nameof(AnyErrors)); }); }
-		public string RunningTime { get => _runningTime; set => Dispatcher.UIThread.Invoke(() => { this.RaiseAndSetIfChanged(ref _runningTime, value); }); }
+		public string? RunningTime { get => _runningTime; set => Dispatcher.UIThread.Invoke(() => { this.RaiseAndSetIfChanged(ref _runningTime, value); }); }
 		public bool ProgressBarVisible { get => _progressBarVisible; set => Dispatcher.UIThread.Invoke(() => { this.RaiseAndSetIfChanged(ref _progressBarVisible, value); }); }
 		public bool AnyCompleted => CompletedCount > 0;
 		public bool AnyQueued => QueuedCount > 0;
@@ -89,7 +91,7 @@ namespace LibationAvalonia.ViewModels
 
 		public decimal SpeedLimitIncrement { get; private set; }
 
-		private async void Queue_CompletedCountChanged(object sender, int e)
+		private async void Queue_CompletedCountChanged(object? sender, int e)
 		{
 			int errCount = Queue.Completed.Count(p => p.Result is ProcessBookResult.FailedAbort or ProcessBookResult.FailedSkip or ProcessBookResult.FailedRetry or ProcessBookResult.ValidationFail);
 			int completeCount = Queue.Completed.Count(p => p.Result is ProcessBookResult.Success);
@@ -98,7 +100,7 @@ namespace LibationAvalonia.ViewModels
 			CompletedCount = completeCount;
 			await Dispatcher.UIThread.InvokeAsync(() => this.RaisePropertyChanged(nameof(Progress)));
 		}
-		private async void Queue_QueuededCountChanged(object sender, int cueCount)
+		private async void Queue_QueuededCountChanged(object? sender, int cueCount)
 		{
 			QueuedCount = cueCount;
 			await Dispatcher.UIThread.InvokeAsync(() => this.RaisePropertyChanged(nameof(Progress)));
@@ -218,13 +220,17 @@ namespace LibationAvalonia.ViewModels
 
 				while (Queue.MoveNext())
 				{
-					var nextBook = Queue.Current;
+					if (Queue.Current is not ProcessBookViewModel nextBook)
+					{
+						Serilog.Log.Logger.Information("Current queue item is empty.");
+						continue;
+					}
 
-					Serilog.Log.Logger.Information("Begin processing queued item. {item_LibraryBook}", nextBook?.LibraryBook);
+					Serilog.Log.Logger.Information("Begin processing queued item. {item_LibraryBook}", nextBook.LibraryBook);
 
 					var result = await nextBook.ProcessOneAsync();
 
-					Serilog.Log.Logger.Information("Completed processing queued item: {item_LibraryBook}\r\nResult: {result}", nextBook?.LibraryBook, result);
+					Serilog.Log.Logger.Information("Completed processing queued item: {item_LibraryBook}\r\nResult: {result}", nextBook.LibraryBook, result);
 
 					if (result == ProcessBookResult.ValidationFail)
 						Queue.ClearCurrent();
@@ -256,7 +262,7 @@ This error appears to be caused by a temporary interruption of service that some
 			}
 		}
 
-		private void CounterTimer_Tick(object state)
+		private void CounterTimer_Tick(object? state)
 		{
 			string timeToStr(TimeSpan time)
 			{
@@ -273,6 +279,6 @@ This error appears to be caused by a temporary interruption of service that some
 	{
 		public DateTime LogDate { get; init; }
 		public string LogDateString => LogDate.ToShortTimeString();
-		public string LogMessage { get; init; }
+		public string? LogMessage { get; init; }
 	}
 }

Source/LibationAvalonia/ViewModels/ProductsDisplayViewModel.cs

@@ -104,6 +104,9 @@ namespace LibationAvalonia.ViewModels
 
 		internal async Task BindToGridAsync(List<LibraryBook> dbBooks)
 		{
+			if (dbBooks == null)
+				throw new ArgumentNullException(nameof(dbBooks));
+
 			//Get the UI thread's synchronization context and set it on the current thread to ensure
 			//it's available for GetAllProductsAsync and GetAllSeriesEntriesAsync
 			var sc = await Dispatcher.UIThread.InvokeAsync(() => AvaloniaSynchronizationContext.Current);
@@ -155,12 +158,11 @@ namespace LibationAvalonia.ViewModels
 		/// </summary>
 		internal async Task UpdateGridAsync(List<LibraryBook> dbBooks)
 		{
+			if (dbBooks == null)
+				throw new ArgumentNullException(nameof(dbBooks));
+
 			if (GridEntries == null)
-			{
+				throw new InvalidOperationException($"Must call {nameof(BindToGridAsync)} before calling {nameof(UpdateGridAsync)}");
-				//always bind before updating. Binding creates GridEntries.
-				await BindToGridAsync(dbBooks);
-				return;
-			}
 
 			#region Add new or update existing grid entries
 

Source/LibationAvalonia/ViewModels/RowComparer.cs

@@ -3,17 +3,18 @@ using LibationUiBase.GridView;
 using System.ComponentModel;
 using System.Reflection;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels
 {
 	internal class RowComparer : RowComparerBase
 	{
-		private static readonly PropertyInfo HeaderCellPi = typeof(DataGridColumn).GetProperty("HeaderCell", BindingFlags.NonPublic | BindingFlags.Instance);
+		private static readonly PropertyInfo? HeaderCellPi = typeof(DataGridColumn).GetProperty("HeaderCell", BindingFlags.NonPublic | BindingFlags.Instance);
-		private static readonly PropertyInfo CurrentSortingStatePi = typeof(DataGridColumnHeader).GetProperty("CurrentSortingState", BindingFlags.NonPublic | BindingFlags.Instance);
+		private static readonly PropertyInfo? CurrentSortingStatePi = typeof(DataGridColumnHeader).GetProperty("CurrentSortingState", BindingFlags.NonPublic | BindingFlags.Instance);
 
-		private DataGridColumn Column { get; init; }
+		private DataGridColumn? Column { get; }
-		public override string PropertyName { get; set; }
+		public override string? PropertyName { get; set; }
 
-		public RowComparer(DataGridColumn column)
+		public RowComparer(DataGridColumn? column)
 		{
 			Column = column;
 			PropertyName = Column?.SortMemberPath ?? nameof(IGridEntry.DateAdded);
@@ -22,7 +23,7 @@ namespace LibationAvalonia.ViewModels
 		//Avalonia doesn't expose the column's CurrentSortingState, so we must get it through reflection
 		protected override ListSortDirection GetSortOrder()
 			=> Column is null ? ListSortDirection.Descending
-			: CurrentSortingStatePi.GetValue(HeaderCellPi.GetValue(Column)) is ListSortDirection lsd ? lsd
+			: CurrentSortingStatePi?.GetValue(HeaderCellPi?.GetValue(Column)) is ListSortDirection lsd ? lsd
 			: ListSortDirection.Descending;
 	}
 }

Source/LibationAvalonia/ViewModels/Settings/AudioSettingsVM.cs

@@ -8,6 +8,7 @@ using ReactiveUI;
 using System;
 using System.Linq;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels.Settings
 {
 	public class AudioSettingsVM : ViewModelBase
@@ -33,17 +34,13 @@ namespace LibationAvalonia.ViewModels.Settings
 		= new(
 			new[]
 			{
-				NAudio.Lame.EncoderQuality.High,
+			NAudio.Lame.EncoderQuality.High,
-				NAudio.Lame.EncoderQuality.Standard,
+			NAudio.Lame.EncoderQuality.Standard,
-				NAudio.Lame.EncoderQuality.Fast,
+			NAudio.Lame.EncoderQuality.Fast,
 			});
 
 
 		public AudioSettingsVM(Configuration config)
-		{
-			LoadSettings(config);
-		}
-		public void LoadSettings(Configuration config)
 		{
 			CreateCueSheet = config.CreateCueSheet;
 			CombineNestedChapterTitles = config.CombineNestedChapterTitles;
@@ -57,7 +54,7 @@ namespace LibationAvalonia.ViewModels.Settings
 			MergeOpeningAndEndCredits = config.MergeOpeningAndEndCredits;
 			StripAudibleBrandAudio = config.StripAudibleBrandAudio;
 			StripUnabridged = config.StripUnabridged;
-			ChapterTitleTemplate = config.ChapterTitleTemplate;
+			_chapterTitleTemplate = config.ChapterTitleTemplate;
 			DecryptToLossy = config.DecryptToLossy;
 			MoveMoovToBeginning = config.MoveMoovToBeginning;
 			LameTargetBitrate = config.LameTargetBitrate;
@@ -67,7 +64,7 @@ namespace LibationAvalonia.ViewModels.Settings
 			LameBitrate = config.LameBitrate;
 			LameVBRQuality = config.LameVBRQuality;
 
-			SelectedSampleRate = SampleRates.SingleOrDefault(s => s.Value == config.MaxSampleRate);
+			SelectedSampleRate = SampleRates.SingleOrDefault(s => s.Value == config.MaxSampleRate) ?? SampleRates[0];
 			SelectedEncoderQuality = config.LameEncoderQuality;
 		}
 

Source/LibationAvalonia/ViewModels/Settings/DownloadDecryptSettingsVM.cs

@@ -3,6 +3,7 @@ using LibationFileManager;
 using ReactiveUI;
 using System.Collections.Generic;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels.Settings
 {
 	public class DownloadDecryptSettingsVM : ViewModelBase
@@ -15,7 +16,16 @@ namespace LibationAvalonia.ViewModels.Settings
 		public DownloadDecryptSettingsVM(Configuration config)
 		{
 			Config = config;
-			LoadSettings(config);
+			BadBookAsk = config.BadBook is Configuration.BadBookAction.Ask;
+			BadBookAbort = config.BadBook is Configuration.BadBookAction.Abort;
+			BadBookRetry = config.BadBook is Configuration.BadBookAction.Retry;
+			BadBookIgnore = config.BadBook is Configuration.BadBookAction.Ignore;
+			_folderTemplate = config.FolderTemplate;
+			_fileTemplate = config.FileTemplate;
+			_chapterFileTemplate = config.ChapterFileTemplate;
+			InProgressDirectory = config.InProgress;
+			UseCoverAsFolderIcon = config.UseCoverAsFolderIcon;
+			SaveMetadataToFile = config.SaveMetadataToFile;
 		}
 
 		public List<Configuration.KnownDirectories> KnownDirectories { get; } = new()
@@ -28,20 +38,6 @@ namespace LibationAvalonia.ViewModels.Settings
 			Configuration.KnownDirectories.LibationFiles
 		};
 
-		public void LoadSettings(Configuration config)
-		{
-			BadBookAsk = config.BadBook is Configuration.BadBookAction.Ask;
-			BadBookAbort = config.BadBook is Configuration.BadBookAction.Abort;
-			BadBookRetry = config.BadBook is Configuration.BadBookAction.Retry;
-			BadBookIgnore = config.BadBook is Configuration.BadBookAction.Ignore;
-			FolderTemplate = config.FolderTemplate;
-			FileTemplate = config.FileTemplate;
-			ChapterFileTemplate = config.ChapterFileTemplate;
-			InProgressDirectory = config.InProgress;
-			UseCoverAsFolderIcon = config.UseCoverAsFolderIcon;
-			SaveMetadataToFile = config.SaveMetadataToFile;
-		}
-
 		public void SaveSettings(Configuration config)
 		{
 			config.BadBook
@@ -62,10 +58,10 @@ namespace LibationAvalonia.ViewModels.Settings
 		public string UseCoverAsFolderIconText { get; } = Configuration.GetDescription(nameof(Configuration.UseCoverAsFolderIcon));
 		public string SaveMetadataToFileText { get; } = Configuration.GetDescription(nameof(Configuration.SaveMetadataToFile));
 		public string BadBookGroupboxText { get; } = Configuration.GetDescription(nameof(Configuration.BadBook));
-		public string BadBookAskText { get; } = Configuration.BadBookAction.Ask.GetDescription();
+		public string BadBookAskText { get; } = Configuration.BadBookAction.Ask.GetDescription() ?? nameof(Configuration.BadBookAction.Ask);
-		public string BadBookAbortText { get; } = Configuration.BadBookAction.Abort.GetDescription();
+		public string BadBookAbortText { get; } = Configuration.BadBookAction.Abort.GetDescription() ?? nameof(Configuration.BadBookAction.Abort);
-		public string BadBookRetryText { get; } = Configuration.BadBookAction.Retry.GetDescription();
+		public string BadBookRetryText { get; } = Configuration.BadBookAction.Retry.GetDescription() ?? nameof(Configuration.BadBookAction.Retry);
-		public string BadBookIgnoreText { get; } = Configuration.BadBookAction.Ignore.GetDescription();
+		public string BadBookIgnoreText { get; } = Configuration.BadBookAction.Ignore.GetDescription() ?? nameof(Configuration.BadBookAction.Ignore);
 		public string FolderTemplateText { get; } = Configuration.GetDescription(nameof(Configuration.FolderTemplate));
 		public string FileTemplateText { get; } = Configuration.GetDescription(nameof(Configuration.FileTemplate));
 		public string ChapterFileTemplateText { get; } = Configuration.GetDescription(nameof(Configuration.ChapterFileTemplate));

Source/LibationAvalonia/ViewModels/Settings/ImportSettingsVM.cs

@@ -1,15 +1,11 @@
 using LibationFileManager;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels.Settings
 {
 	public class ImportSettingsVM
 	{
 		public ImportSettingsVM(Configuration config)
-		{
-			LoadSettings(config);
-		}
-
-		public void LoadSettings(Configuration config)
 		{
 			AutoScan = config.AutoScan;
 			ShowImportedStats = config.ShowImportedStats;

Source/LibationAvalonia/ViewModels/Settings/ImportantSettingsVM.cs

@@ -7,6 +7,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 
+#nullable enable
 namespace LibationAvalonia.ViewModels.Settings
 {
 	public class ImportantSettingsVM : ViewModelBase
@@ -18,12 +19,8 @@ namespace LibationAvalonia.ViewModels.Settings
 		public ImportantSettingsVM(Configuration config)
 		{
 			this.config = config;
-			LoadSettings(config);
-		}
 
-		public void LoadSettings(Configuration config)
+			BooksDirectory = config.Books?.PathWithoutPrefix ?? Configuration.DefaultBooksDirectory;
-		{
-			BooksDirectory = config.Books.PathWithoutPrefix;
 			SavePodcastsToParentFolder = config.SavePodcastsToParentFolder;
 			OverwriteExisting = config.OverwriteExisting;
 			CreationTime = DateTimeSources.SingleOrDefault(v => v.Value == config.CreationTime) ?? DateTimeSources[0];
@@ -32,9 +29,9 @@ namespace LibationAvalonia.ViewModels.Settings
 			GridScaleFactor = scaleFactorToLinearRange(config.GridScaleFactor);
 			GridFontScaleFactor = scaleFactorToLinearRange(config.GridFontScaleFactor);
 
-			ThemeVariant = initialThemeVariant = Configuration.Instance.GetString(propertyName: nameof(ThemeVariant));
+			themeVariant = initialThemeVariant = Configuration.Instance.GetString(propertyName: nameof(ThemeVariant)) ?? "";
 			if (string.IsNullOrWhiteSpace(initialThemeVariant))
-				ThemeVariant = initialThemeVariant = "System";
+				themeVariant = initialThemeVariant = "System";
 		}
 
 		public void SaveSettings(Configuration config)
@@ -100,14 +97,17 @@ namespace LibationAvalonia.ViewModels.Settings
 			get => themeVariant;
 			set
 			{
+				var changed = !value.Equals(themeVariant);
 				this.RaiseAndSetIfChanged(ref themeVariant, value);
-				App.Current.RequestedThemeVariant = themeVariant switch
+
-				{
+				if (changed && App.Current is Avalonia.Application app)
-					nameof(Avalonia.Styling.ThemeVariant.Dark) => Avalonia.Styling.ThemeVariant.Dark,
+					app.RequestedThemeVariant = themeVariant switch
-					nameof(Avalonia.Styling.ThemeVariant.Light) => Avalonia.Styling.ThemeVariant.Light,
+					{
-					// "System"
+						nameof(Avalonia.Styling.ThemeVariant.Dark) => Avalonia.Styling.ThemeVariant.Dark,
-					_ => Avalonia.Styling.ThemeVariant.Default
+						nameof(Avalonia.Styling.ThemeVariant.Light) => Avalonia.Styling.ThemeVariant.Light,
-				};
+						// "System"
+						_ => Avalonia.Styling.ThemeVariant.Default
+					};
 			}
 		}
 	}

Source/LibationFileManager/Configuration.HelpText.cs

@@ -30,7 +30,7 @@ namespace LibationFileManager
         }
         .AsReadOnly();
 
-        public static string? GetHelpText(string settingName)
+        public static string GetHelpText(string settingName)
-            => HelpText.TryGetValue(settingName, out var value) ? value : null;
+            => HelpText.TryGetValue(settingName, out var value) ? value : "";
-	}
+    }
 }

Source/LibationFileManager/Configuration.PersistentSettings.cs

@@ -82,7 +82,7 @@ namespace LibationFileManager
 
 		public string SettingsFilePath => Path.Combine(LibationFiles, "Settings.json");
 
-		public static string? GetDescription(string propertyName)
+		public static string GetDescription(string propertyName)
 		{
 			var attribute = typeof(Configuration)
 				.GetProperty(propertyName)
@@ -90,7 +90,7 @@ namespace LibationFileManager
 				.SingleOrDefault()
 				as DescriptionAttribute;
 
-			return attribute?.Description;
+			return attribute?.Description ?? $"[{propertyName}]";
 		}
 
 		public bool Exists(string propertyName) => Settings.Exists(propertyName);
@@ -118,12 +118,15 @@ namespace LibationFileManager
 
 		// temp/working dir(s) should be outside of dropbox
 		[Description("Temporary location of files while they're in process of being downloaded and decrypted.\r\nWhen decryption is complete, the final file will be in Books location\r\nRecommend not using a folder which is backed up real time. Eg: Dropbox, iCloud, Google Drive")]
-		public string InProgress { get
+		public string InProgress
+		{
+			get
 			{
 				var tempDir = GetString();
 				return string.IsNullOrWhiteSpace(tempDir) ? WinTemp : tempDir;
 			}
-			set => SetString(value); }
+			set => SetString(value);
+		}
 
 		[Description("Allow Libation to fix up audiobook metadata")]
 		public bool AllowLibationFixup { get => GetNonString(defaultValue: true); set => SetNonString(value); }
@@ -162,10 +165,10 @@ namespace LibationFileManager
 		public NAudio.Lame.EncoderQuality LameEncoderQuality { get => GetNonString(defaultValue: NAudio.Lame.EncoderQuality.High); set => SetNonString(value); }
 
 		[Description("Lame encoder downsamples to mono")]
-		public bool LameDownsampleMono {  get => GetNonString(defaultValue: true); set => SetNonString(value); }
+		public bool LameDownsampleMono { get => GetNonString(defaultValue: true); set => SetNonString(value); }
 
 		[Description("Lame target bitrate [16,320]")]
-		public int LameBitrate {  get => GetNonString(defaultValue: 64); set => SetNonString(value); }
+		public int LameBitrate { get => GetNonString(defaultValue: 64); set => SetNonString(value); }
 
 		[Description("Restrict encoder to constant bitrate?")]
 		public bool LameConstantBitrate { get => GetNonString(defaultValue: false); set => SetNonString(value); }
@@ -179,8 +182,8 @@ namespace LibationFileManager
 		private static readonly EquatableDictionary<string, bool> DefaultColumns = new(
 			new KeyValuePair<string, bool>[]
 			{
-				new ("SeriesOrder", false),
+			new ("SeriesOrder", false),
-				new ("LastDownload", false)
+			new ("LastDownload", false)
 			});
 
 		[Description("A Dictionary of GridView data property names and bool indicating its column's visibility in ProductsGrid")]

Source/LibationFileManager/QuickFilters.cs

@@ -46,7 +46,7 @@ namespace LibationFileManager
 
         // Note that records overload equality automagically, so should be able to
         // compare these the same way as comparing simple strings.
-        public record NamedFilter(string Filter, string Name)
+        public record NamedFilter(string Filter, string? Name)
         {
             public string Filter { get; set; } = Filter;
             public string? Name { get; set; } = Name;

Source/LibationUiBase/GridView/RowComparerBase.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 
+#nullable enable
 namespace LibationUiBase.GridView
 {
 	/// <summary>
@@ -11,67 +12,10 @@ namespace LibationUiBase.GridView
 	/// </summary>
 	public abstract class RowComparerBase : IComparer, IComparer<IGridEntry>, IComparer<object>
 	{
-		public abstract string PropertyName { get; set; }
+		public abstract string? PropertyName { get; set; }
 
-		public int Compare(object x, object y)
+		public int Compare(object? x, object? y)
-		{
+			=> Compare(x as IGridEntry, y as IGridEntry);
-			if (x is null && y is not null) return -1;
-			if (x is not null && y is null) return 1;
-			if (x is null && y is null) return 0;
-
-			var geA = (IGridEntry)x;
-			var geB = (IGridEntry)y;
-
-			var sortDirection = GetSortOrder();
-
-			ISeriesEntry parentA = null;
-			ISeriesEntry parentB = null;
-
-			if (geA is ILibraryBookEntry lbA && lbA.Parent is ISeriesEntry seA)
-				parentA = seA;
-			if (geB is ILibraryBookEntry lbB && lbB.Parent is ISeriesEntry seB)
-				parentB = seB;
-
-			//both a and b are top-level grid entries
-			if (parentA is null && parentB is null)
-				return InternalCompare(geA, geB);
-
-			//a is top-level, b is a child
-			if (parentA is null && parentB is not null)
-			{
-				// b is a child of a, parent is always first
-				if (parentB == geA)
-					return sortDirection is ListSortDirection.Ascending ? -1 : 1;
-				else
-					return InternalCompare(geA, parentB);
-			}
-
-			//a is a child, b is a top-level
-			if (parentA is not null && parentB is null)
-			{
-				// a is a child of b, parent is always first
-				if (parentA == geB)
-					return sortDirection is ListSortDirection.Ascending ? 1 : -1;
-				else
-					return InternalCompare(parentA, geB);
-			}
-
-			//both are children of the same series
-			if (parentA == parentB)
-			{
-				//Podcast episodes usually all have the same PurchaseDate and DateAdded property:
-				//the date that the series was added to the library. So when sorting by PurchaseDate
-				//and DateAdded, compare SeriesOrder instead..
-				return PropertyName switch
-				{
-					nameof(IGridEntry.DateAdded) or nameof (IGridEntry.PurchaseDate) => geA.SeriesOrder.CompareTo(geB.SeriesOrder),
-					_ => InternalCompare(geA, geB),
-				};
-			}
-
-			//a and b are children of different series.
-			return InternalCompare(parentA, parentB);
-		}
 
 		protected abstract ListSortDirection GetSortOrder();
 
@@ -80,7 +24,7 @@ namespace LibationUiBase.GridView
 			var val1 = x.GetMemberValue(PropertyName);
 			var val2 = y.GetMemberValue(PropertyName);
 
-			var compare =  x.GetMemberComparer(val1.GetType()).Compare(val1, val2);
+			var compare = x.GetMemberComparer(val1.GetType()).Compare(val1, val2);
 
 			return compare == 0 && x.Liberate.IsSeries && y.Liberate.IsSeries
 				//Both a and b are series parents and compare as equal, so break the tie.
@@ -88,9 +32,66 @@ namespace LibationUiBase.GridView
 				: compare;
 		}
 
-		public int Compare(IGridEntry x, IGridEntry y)
+		public int Compare(IGridEntry? geA, IGridEntry? geB)
 		{
-			return Compare((object)x, y);
+			if (geA is null && geB is not null) return -1;
+			if (geA is not null && geB is null) return 1;
+			if (geA is null || geB is null) return 0;
+
+			var sortDirection = GetSortOrder();
+
+			ISeriesEntry? parentA = null;
+			ISeriesEntry? parentB = null;
+
+			if (geA is ILibraryBookEntry lbA && lbA.Parent is ISeriesEntry seA)
+				parentA = seA;
+			if (geB is ILibraryBookEntry lbB && lbB.Parent is ISeriesEntry seB)
+				parentB = seB;
+
+			//both entries are children
+			if (parentA != null && parentB != null)
+			{
+				//both are children of the same series
+				if (parentA == parentB)
+				{
+					//Podcast episodes usually all have the same PurchaseDate and DateAdded property:
+					//the date that the series was added to the library. So when sorting by PurchaseDate
+					//and DateAdded, compare SeriesOrder instead..
+					return PropertyName switch
+					{
+						nameof(IGridEntry.DateAdded) or nameof(IGridEntry.PurchaseDate) => geA.SeriesOrder.CompareTo(geB.SeriesOrder),
+						_ => InternalCompare(geA, geB),
+					};
+				}
+				else
+					//a and b are children of different series.
+					return InternalCompare(parentA, parentB);
+			}
+
+			//a is top-level, b is a child
+			else if (parentA is null && parentB is not null)
+			{
+				// b is a child of a, parent is always first
+				if (parentB == geA)
+					return sortDirection is ListSortDirection.Ascending ? -1 : 1;
+				else
+					return InternalCompare(geA, parentB);
+			}
+			//a is a child, b is a top-level
+			else if (parentA is not null && parentB is null)
+			{
+				// a is a child of b, parent is always first
+				if (parentA == geB)
+					return sortDirection is ListSortDirection.Ascending ? 1 : -1;
+				else
+					return InternalCompare(parentA, geB);
+			}
+			//parentA and parentB are null
+			else
+			{
+				//both a and b are top-level grid entries
+				return InternalCompare(geA, geB);
+			}
 		}
 	}
 }