We've found these exceptions in logs:
Job exception: undefined method `destroy!' for nil:NilClass
/var/www/discourse/plugins/chat/lib/chat/notifier.rb:102:in `block in notify_edit'
/var/www/discourse/plugins/chat/lib/chat/notifier.rb💯in `each'
/var/www/discourse/plugins/chat/lib/chat/notifier.rb💯in `notify_edit'
/var/www/discourse/plugins/chat/app/jobs/regular/chat/send_message_notifications.rb:18:in `execute'
In the past, we were creating `chat_mention` records only for sending notifications, so every mention record had a related notification. It isn't the case anymore (since fa543cda). This PR fixes the problem by making sure the notification exists before trying to remove it. Also, we shouldn't be deleting a `chat_mention` record itself, only a notification, this PR fixes that too.
It's quite hard to reproduce this bug locally, I wasn't able to do so, the logic in this class is quite complicated, that's why I'm not adding a test. Also, when looking at this I realized that this method isn't in a fully correct state now, I suspect sometimes some notifications may not be delivered after someone edits a chat message and adds new mentions to it. I'm going to refactor and simplify the method in a subsequent PR.
26543a5b59