I was speaking loosely and lumped "run forever with no progress" and "crash the program" into the same space; my apologies for the lack of clarity. A more prec

I was speaking loosely and lumped "run forever with no progress" and "crash the program" into the same space; my apologies for the lack of clarity. A more precise way to say it is "regular functions either return or we're in a bad place (or we're in a very special circumstance, like 'this program burns cycles on purpose because the scheduler requires something to be running')." For async functions, failure to progress to a returnable state is expected behavior, so the whole system needs to be built around allowing computational progress while waiting for the state to change to where the return can occur.