The suggestion:
When VM is closing, coroutine.close() should be automatically invoked for every non-dead coroutine in the VM.
Dead coroutines (after an error is raised) can have non-closed to-be-closed variables too.
So, the suggestion is: All coroutines in the VM should be implicitly closed on VM exit.
Of course it would be better to implicitly close dead coroutines at the moment they become dead.
