Inform user that they need to shutdown when `Persist` functions start returning failures

[johncantrell97]

There's a TODO in the Persist implementation provided that says:

// TODO: We really need a way for the persister to inform the user that its time to crash/shut
// down once these start returning failure.
// A PermanentFailure implies we need to shut down since we're force-closing channels without
// even broadcasting!

@TheBlueMatt thinks using Event::ChannelClosed here might make sense.