Hi.

I find a bug with the book enchanted and anvil.
I think it's because of ench négative of my diamond sword.

To reproduce :

1- Give item with custom ench négative

/give @p minecraft:diamond_sword{ench:[{id:-1,lvl:0}]}

2- Take a enchanted book "sharpness V" for example

3- Use enchanted book with sword in anvil

4- CRASH xD