Issue:
-> I was using Projectile>exchange>AOEx2 and when exchanging dirt with stone it crashed me.

Crashlog:
-> https://pastebin.com/YZWK7kUL

Mod Version:
-> Ars Nouveau 1.20.1-4.6.0-all

does the same thing to me. same version. I tried different configuration of the spell like touch or projectile, with aoe, no aoe, different block to replace and it just always crash with the book disappearing from the hotbar afterward when loading the world again.

https://pastebin.com/rMP3mAQB

Should be fixed next version, hopefully here in a few hours.

yup it works!