Mutes don't report when a role id no longer exists #26
Description
Just recently ran into a problem where mutes stopped working. The cause was not code-related, but rather that the Role previously associated with muting had a newly assigned Role ID. The bot failed requests to mute silently, even to the point that it stopped writing Mute Cases to the local data repository.
To fix this, a check should be added to the "mute" command. If it fails to result in a known Role, it should error and notify. Such a notification would have saved almost a month of downtime for this feature.