Some cleanup

Application/MainWindow/CommandLine.cs

@@ -26,7 +26,7 @@ namespace FeedCenter
             var endPosition = commandLine.IndexOf(" ", startPosition, StringComparison.Ordinal);
 
             // Extract the feed URL
-            var feedUrl = commandLine.Substring(startPosition, endPosition - startPosition);
+            var feedUrl = commandLine[startPosition..endPosition];
 
             // Add the HTTP protocol by default
             feedUrl = "http://" + feedUrl;

Application/MainWindow/FeedCreation.cs

@@ -63,7 +63,7 @@ namespace FeedCenter
             }
 
             // Read the feed for the first time
-            var feedReadResult = feed.Read(_database);
+            var feedReadResult = feed.Read();
 
             // See if we read the feed okay
             if (feedReadResult == FeedReadResult.Success)

Application/MainWindow/FeedReading.cs

@@ -159,7 +159,7 @@ namespace FeedCenter
             foreach (var feed in feedsToRead)
             {
                 // Read the feed
-                database.SaveChanges(() => feed.Read(database, workerInput.ForceRead));
+                database.SaveChanges(() => feed.Read(workerInput.ForceRead));
 
                 // Increment progress
                 currentProgress += 1;

Application/MainWindow/MainWindow.xaml.cs

@@ -131,9 +131,8 @@ namespace FeedCenter
                             break;
                         case Dock.Left:
                         case Dock.Right:
-                            throw new NotSupportedException();
                         default:
-                            throw new ArgumentOutOfRangeException(nameof(Settings.Default.ToolbarLocation));
+                            throw new NotSupportedException();
                     }
 
                     break;
@@ -153,8 +152,8 @@ namespace FeedCenter
             _database.Refresh();
 
             _feedList = _currentCategory == null
-                ? _database.Feeds
-                : _database.Feeds.Where(feed => feed.Category.Id == _currentCategory.Id);
+                ? _database.Feeds.ToList()
+                : _database.Feeds.Where(feed => feed.Category.Id == _currentCategory.Id).ToList();
 
             UpdateToolbarButtonState();