I disabled Creative mode-only editing and attempted to edit an item, and the game immediately crashed. Strangely, it only happens if opening the editor in the inventory GUI, and not whilst holding the item and pressing the key.

Hi, can you send a crash report?

crash-2021-04-11_08.24.09-client.txt

Thanks! You can avoid this crash by closing the Recipe Book. I'll investigate to fix the bug.

Crash reason: the "key press" event kept propagating to the inventory screen after opening the editor screen, causing a crash when the recipe book is open, due to a NullPointerException after the inventory screen was cleaned up and the recipe book GUI removed.
Fix: consume (cancel) the event right after opening the editor screen so it doesn't propagate to the inventory screen.

Fixed in version 1.2.5 (click to download)