Steps to Reproduce the Crash

1 toggle cheat mode in JEI
2 search for End remastered mod
3 cheat in 1 eye from mod

Mod Pack URL (Optional)

No response

Mod Pack Version (Optional)

No response

Extra Notes (Optional)

No response

Crash Report

https://gist.github.com/IamGallito/5c7e7c7ac77ff0d29f51df88122ab54c

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Also getting this error on my own pack

Resolved, install REI instead for fabric loader

Thanks for the report!
This seems to be happening when JEI calls Minecraft to tell it to sync the inventory to the client.
I think there is another mod involved that is causing the underlying issue, can you try removing some mods until this issue goes away, in order to identify which mod is causing the problem?