Minecraft and Mod version 🐞
Minecraft: 1.21.1
Mod: 5.9.0

Description of the crash 💥
A few moments after opening the "change model" GUI inside the NPC editor, the game will crash, with or without any further input.

Steps to reproduce the crash ⚙️

1. Spawn an NPC
2. Access the editor
3. Open the "change model" GUI

Expected behavior before the crash ✔️
Ability to scroll through the different entities, and choose one that the NPC will change into.

Logs 📝
https://gist.github.com/PogNoodleGit/42bebbaedb290d602770ae5a20d4ec2f

Additional context 📋

This happens on a server, and doesn't occur in singleplayer. The modlist and versions are the same across client and server. However, the client has client-side mods as well. I also found that copying the mods from the server into the client only, resolves the problem, so I assume it's an incompatibility between Easy NPC and one of the client-side mods.

I found that the issue was between the client having the distant friends mod and the server not having it. I made the post and solved it myself 10 mins later RIP