Updating readme

Aurora/Design/Views/Party/PartyViewModel.cs

@@ -185,7 +185,10 @@ namespace Aurora.Design.Views.Party
         /// <returns></returns>
         public override Task OnInactive()
         {
-            this._eventCancellationTokenSource.Cancel();
+            if(this._eventCancellationTokenSource != null){
+                this._eventCancellationTokenSource.Cancel();
+            }
+            
             return Task.FromResult<object>(null);
         }