Don't double decremente MessageCount when deleting disappearing messages

Author: golf1052

Signal-Windows/Controls/Conversation.xaml.cs

@@ -440,10 +440,13 @@ private void MarkBottommostMessageRead()
                 {
                     LastMarkReadRequest = rawBottomIndex;
                     var msg = ((IMessageView)Collection[bottomIndex]).Model;
-                    Task.Run(async () =>
+                    if (msg.Author != null)
                     {
-                        await App.Handle.SetMessageRead(msg);
-                    });
+                        Task.Run(async () =>
+                        {
+                            await App.Handle.SetMessageRead(msg);
+                        });
+                    }
                 }
             }
         }

Signal-Windows/Controls/VirtualizedMessagesCollection.cs

@@ -212,7 +212,7 @@ public void Remove(SignalMessage signalMessage)
 
                 if (deletedItem)
                 {
-                    Conversation.MessagesCount--;
+                    Conversation.MessagesCount -= 1;
                     CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removedMessage, finalVirtualIndex));
                 }
             }

Signal-Windows/ViewModels/MainPageViewModel.cs

@@ -404,7 +404,8 @@ public void HandleMessageDelete(SignalMessage message)
             {
                 View.Thread.HandleDeleteMesage(message);
                 var localConversation = ConversationsDictionary[SelectedThread.ThreadId];
-                localConversation.MessagesCount -= 1;
+                // don't need to decrement MessagesCount by 1 because it was already decremented by HandleDeleteMessage
+                // specifically decremented by VirtualizedMessageCollection.Remove()
                 localConversation.LastMessage = null;
                 localConversation.LastMessageId = null;
                 localConversation.LastSeenMessage = null;