Add link to "(none) note filter" error message

[BobvanSchendel]

Describe the bug

I have used anki-morphs before and it works well. Today I using a new laptop with an older version of my deck. Uninstalled MorphMan (which was still installed there), installed Ankimorphs and tried to recalc and was hit by the error message: "Found a note filter containing a "(none)" option. Please select something else" I don't think I changed anything about my deck other than deleting a few random cards so I'm not sure what to do about this. I can't find anything in the documentation or open issues about this so probably just need to be pointed in the right direction.

Steps to reproduce the behavior

Expected behavior

Screenshots

My setup

• Operating System:
• Anki Version:
• AnkiMorphs Version:

Additional context