Exceptions raised in `Spawn`ed cothread can be lost

[Araneidae]

The Spawn option raise_on_wait causes reporting of any exception terminating the spawned cothread to be deferred until .Wait() is called on the associated cothread, for instance:

def task(): raise Exception('Die')
def test():
    action = Spawn(task, raise_on_wait = True)
    action.Wait()

Unfortunately if .Wait() is never called then the associated exception is never reported.

It might be possible to fix this by added a __del__ method to Spawn and reporting any exception that hasn't already been reported.

[Araneidae]

Alas. A quick experiment indicates that __del__ isn't called, there are probably reference count loops that can't easily be avoided.

[AlexanderWells-diamond]

Can we do anything with atexit functions?

[Araneidae]

That would be very late, and would require the admin and overhead of maintaining a list of all uncaught exceptions. An interesting idea though...