Snapshots are an optimization to reduce recovery time and therefore the thought has been that it doesn't matter if snapshot could not be loaded.

However, when events are deleted it's not safe to just replay the remaining events. It can result in starting the actor with inconsistent state, since some information was lost (removed).

We need to add LoadSnapshotFailure message and use that in the SnapshotStore if the loadAsync Future fails. The persistent actor should be stopped in the same way as for other replay failures.