Fix the check on the UiDispatcher; it does not need the CheckContext.

Rubberduck.Parsing/UIContext/UiDispatcher.cs

@@ -95,7 +95,7 @@ public Task<T> StartTask<T>(Func<T> func, TaskCreationOptions options = TaskCrea
 
         private void CheckInitialization()
         {
-            if (!_contextProvider.CheckContext())
+            if (_contextProvider.UiContext == null)
             {
                 throw new InvalidOperationException("UiDispatcher is not initialized. Invoke Initialize() from UI thread first.");
             }