Updater notice when a plugin/theme repository no longer exists

[MulverineX]

Describe the feature request
When a repository in your plugin/theme list is gone, tell the user which plugin/theme.

What Plugin would it be for?
pc-updater

Expected behavior
You will receive a toast when updates are being checked for and a repository remote no longer exists. At the least it will contain the name & type, but it would be nice if there was an uninstall shortcut button included in the toast.