INotifyPropertyChanged.TaskCompleted is null

[StephenCleary]

(From Andy):

Firstly - thank you so much for your very useful library.

I am developing a WinRT app and using your NotifyTaskCompletion classes.
I note that the INotifyPropertyChanged.TaskCompleted property comment says:
"This property never changes and is never null"

However, when mocking up some data using Task.FromResult I have observed INotifyPropertyChanged.TaskCompleted set to null.

In the NotifyTaskCompletionImplementation ctor I see that the TaskCompleted property is only set if (!task.IsCompleted)

Is the comment wrong and should I check Execution.IsCompleted before awaiting Execution.TaskCompleted or is this a bug?

[StephenCleary]

Yes, I would say the implementation is wrong. I'll get a fix out.

[StephenCleary]

This should be fixed in 3.0.1-pre: https://www.nuget.org/packages/Nito.AsyncEx/3.0.1-pre

TaskCompleted will now be set to TaskConstants.Completed if the source task is already completed. Didn't take the time to write unit tests for this type, though. Let me know if this is still a problem.