The bug

As of 23w41a, no error message is displayed when using /advancement to grant an advancement that is already attained, or when trying to revoke an advancement that is not attained.

The error message strings still exist, e.g. commands.advancement.grant.one.to.one.failure, but they are no longer displayed.

How to reproduce

1. /gamerule sendCommandFeedback true
2. /advancement revoke @s everything
3. /advancement revoke @s only story/mine_stone
   → No error message is displayed
4. /advancement grant @s only story/mine_stone
   → You are granted the advancement, and command feedback is displayed
5. /advancement grant @s only story/mine_stone
   → No error message is displayed

Expected results

The following error messages should be displayed:

Couldn't revoke advancement [Stone Age] from <PLAYER> as they don't have it

Couldn't grant advancement [Stone Age] to <PLAYER> as they already have it

These messages are displayed in 23w40a and earlier.