Fixed possible race condition.

FileManager/BackgroundFileSystem.cs

@@ -75,6 +75,8 @@ namespace FileManager
         }
 
         private void UpdateLocalCache(FileSystemEventArgs change) 
+        {
+            lock (fsCache)
             {
                 if (change.ChangeType == WatcherChangeTypes.Deleted)
                 {
@@ -92,28 +94,23 @@ namespace FileManager
                     AddPath(renameChange.FullPath);
                 }
             }
+        }
 
         private void RemovePath(string path)
-        {
-            lock (fsCache)
         {
             var pathsToRemove = fsCache.Where(p => p.StartsWith(path)).ToArray();
 
             foreach (var p in pathsToRemove)
                 fsCache.Remove(p);
         }
-        }
 
         private void AddPath(string path)
-        {
-            lock (fsCache)
         {
             if (File.GetAttributes(path).HasFlag(FileAttributes.Directory))
                 fsCache.AddRange(Directory.EnumerateFiles(path, SearchPattern, SearchOption));
             else
                 fsCache.Add(path);
         }
-        }
 
         #endregion
     }