https://paste.gg/p/anonymous/ef9bf2147a9b4bd0b10f45170c59f272

Also now getting this error. This started to occur after updating Outer End to 0.2.12 which was the fix for the abnormals core update.

MC 1.16.5
Forge 36.1.31
abnormals core 3.2.0
outer end 0.2.12
endergetic 3.0.0

Crash 1 log: https://gist.github.com/judicius/21d4903cfb3a08caf97023c845aea86a
Crash 2 log: https://gist.github.com/judicius/34b5f9d95091632f1a5aec07452d940f

I'm also getting this issue. It happens whenever I try to load a world with certain mods installed. It seems to be related to the tag for blocks which can hold ender fire. I can't seem to reproduce this with only endergetic. So maybe it's a compatibility issue between mods?

Although, It could still be an issue with endergetic itself since I can't seem to consistently reproduce this issue all the time.

Here's my most recent Crash Report: https://gist.github.com/NJL5390/1f30282564dfac5b75f4e77acf689c6f

EDIT: I also sometimes get this crash when using the lava monsters mod (But not all the time): https://gist.github.com/NJL5390/b5d9d0de665fad96afa7b02860ece6b4

This crash looks to be caused by another mod adding incorrect entries to the endergetic:ender_fire_base_blocks tag.
I recommend opening an issue on Outer End's repository.

It is definitely Outer End that is the cause of this. Removing that mod fixes this issue for me. I've opened an issue on their repository here: BlueDuckYT/The-Outer-End#47