I wasnt able to open my inventory without the game crashing with my custom modpack, so I tried it again with just BetterEnd, BetterNether, BClib, Forgified Fabric API, Mutil, Sinytra Connector, Tetra, and this mod and the same thing happened. I also tried to spawn it in to see if it was just that item, but I could not find it through the commands.

crash-2025-03-09_14.15.45-client.txt

Specifically, it only happens when better nether is added

Dammit, I swear it was fine this morning. Hang on.

Whoops, found it. Tetranomicon's items are only registered if the mods that require them are installed. Forgot to add Better Nether to that list. Fixed. 1.6.1 uploaded.