When I was playing on my private server, I was searching for the Sever (enchantment added by AoA) enchantment, but the enchanted books were named "Form" instead (another enchantment added by AoA).
I then searched "Form" to see if I would get enchanted books named Sever, but upon hovering over the enchanted books, my game crashed (The server did not crash, only I did)
This doesn't seem to happen in singleplayer.

My friends could still see the enchantments normally, they were even able to enchant the item and give it to me, and I could hover over it without crashing. It only seems to happen when I do it though (since they likely don't have Foamfix).
Removing Foamfix appears to fix the bug, the books have the right names and it doesn't crash.

Here's the crash report by the way.
https://pastebin.com/0iQETvs0