Describe what you were doing before the crash
Loading game. Found that while looking in the log.

1. See log https://pastebin.com/vRaGBgJe

Crash Log (REQUIRED)
https://pastebin.com/vRaGBgJe

See full log for more information if disired
latest.log

Versions:

• Forge Version: (2838)
• MC Version:1.12.2
• Mod Version:6.0.1

Can I see your configuration file?

As far as I know, only thing I changed was adding biomesoplenty:wasteland to some spawns,
https://pastebin.com/eYwkWeJv

Can you confirm this happens if you delete/rename your config, open a world, and then restart the game and open a world again?

@NickelHub can I please see your mod list? You removed it from latest.txt

@itsmeow I will attempt to recreate it. As I have taken and interest in your mod. I will say this right off of the bat his log has a surprising amount of errors. Also a red flag is Azanors Thaumcraft 6.

I'm gonna put this down to improper configuration. If this pops up again or anyone can find it with a default generated configuration, feel free to comment / re-open