Progressive Bosses 3.4.1-mc1.16.5
Modpack: Mineshaft and Monsters
Crash Report: https://pastebin.com/puzvTBii
Description: The crash seems fairly random however if I am reading the stack trace correctly perhaps there is some issue with certain mobs that might be added with other mods? This particular crash above occured when a mimic decided to attack.

I can't test this with a modpack, I need fewer mods and seems Infernal Expansion might be the cause

No follow up so going to close the issue