Filtered Deck errors break Undo/Redo

[jcznk]

Tested on Anki 25.08b5, Windows 11. I was only able to reproduce the issue with Filtered Deck-related errors.

Steps to reproduce

1. Perform an action (e.g., add a new note).
2. Trigger a Filtered Deck error. For example:
   • Go to a non-filtered deck and press R (rebuild), triggering:
     This action can only be used on a filtered deck
   • Or create a filtered deck that matches 0 cards, triggering:
     No cards matched the provided search. Some cards may have been excluded because they are in a different filtered deck, or suspended.
3. Press Ctrl+Z or go to Edit > Undo.
   • Expected result: The last action is undone.
   • Actual result: Nothing happens.

[abdnh]

Anki clears the undo queue on backend errors, but this is not really needed for some kinds of errors.