Better WebSocket error recovery in EditWatcher and DeletionWatcher

[makyen]

Some of the exceptions logged here indicate we're rebooting sometimes when there's an error on the EditWatcher and/or DeletionWatcher WebSockets. We could use better recovery from WebSocket exceptions in both of these modules (which use similar code, so similar error recover seems reasonable). We already retry the main WebSocket, so it would be reasonable to have somewhat similar code in EditWatcher and DeletionWatcher.