Typically supervisors are monitoring readiness/liveness of the managed process for other reasons; you don't have the number of replicas you've promised if one of the replicas is un-live (perhaps hitting this bug, perhaps internally deadlocked, perhaps internally waiting forever on something the OS doesn't care about, like a certain network request), and you shouldn't be routing network traffic to a service that isn't ready for it.

So while I agree with the other posts that a supervisor can't recover from this state, it can be aware that it's happened. And it's quite common for supervisors to check for readiness and liveness beyond "well the OS says it's running, sounds good to me."