fix potential ArgumentException during shard rebalancing#7367

Aaronontheweb merged 2 commits into

akkadotnet:devakkadotnet/akka.net:devfrom

Aaronontheweb:close-7365-shardRebalanceFailureAaronontheweb/akka.net:close-7365-shardRebalanceFailureCopy head branch name to clipboard