fix: Notifier::prepare() threw \InvalidArgumentException which is dep…

[nickvergessen]

…recated

📝 Summary

If a user has any notifications this log is generated all the time:

OCA\Text\Notification\Notifier::prepare() threw \InvalidArgumentException which is deprecated. Throw \OCP\Notification\UnknownNotificationException when the notification is not known to your notifier and otherwise handle all \InvalidArgumentException yourself.

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits
• Tests (unit, integration and/or end-to-end) passing and the changes are covered with tests
• Documentation (README or documentation) has been updated or is not required

[juliusknorr]

Thanks a lot ❤️