Is this a bug that could/should be fixed?
I don't think this is even a bug, when you yield there has to be a call to 'resume' that receives the values yielded, and there isn't any. You could potentially return the values from coroutine.close but that would mean that coroutine.close could not 'close' the coroutine because it may have to yield potentially multiple times through the cleanup process.
I have trouble thinking of a use case for this to begin with.