Well I learned something new today

Throwing an exception in an actor's PreStart block will not allow the actor to be restarted: https://replit.com/@Aaronontheweb/ActorsPreStart#main.cs

I'm trying to imagine if that's by design or not (it might be since the child actor can't really complete its startup sequence if it fails there.)

Either way, that means this bug is more severe than I thought. We'll get this patched right away.

Originally posted by @Aaronontheweb in #5962 (comment)

One implication of this is that the actor's PostStop method is also never called, which causes functions that depend on PostStop for cleanup such as IWithTimers to never run correctly.