Threaded Wait Dialog example: compiler warning for statement that calls Dispose on object returned by ThreadedWaitDialogHelper.CreateInstance

[shaneharper]

Regarding
(twd as IDisposable).Dispose();
from the Threaded Wait Dialog example:

1. The compiler outputs:

    warning CS8602: Dereference of a possibly null reference.
   

   What should be done to get rid of that warning?

2. Until I saw the example code it had never occurred to me that there could be a need to call Dispose for the object returned by ThreadedWaitDialogHelper.CreateInstance(IVsThreadedWaitDialogFactory). Could a comment be added to the example explaining the need for it? Perhaps the best place to mention it would be in the documentation for CreateInstance.