my server crashed when me and a friend were trying to go through the twillight portal for the first time i asked for help and was told "Ok so there is an exception in the world when doing a tick update. When loading the twilight forest, the game is attempting to spawn random mobs I think."
To Reproduce
Steps to reproduce the behavior:

Crash Log
https://pastebin.com/fkJZ8fQ7

Info (please complete the following information):

• Modpack Version: 3.0 beta
• Server
• Version the world was created on: 1.12

Additional context

A temp fix for this will be implemented in beta 5.

Actually, duplicate of #640