It happened by accident, during the explosion of the digamma rod RBMK, I can’t say for sure that this is falsetweaks, but in Mixins in Stacktrace there are many changes in Tessellator, this of course doesn’t say anything (as there is a crash report about BufferOverflowException), but there is also
net.minecraft. client.renderer.Tessellator.func_78381_a And net.minecraft.client.renderer.WorldRenderer.func_147891_a.
Crash report:
https://pastebin.com/r0mPhqGr

Optifine is mentioned in the title (there is no mention of it in crash report), just keep in mind that it was present during the crash.
I’ll say right away that it’s not always possible to reproduce it (it only happened 2 times, about 15 attempts)

Oh, yeah, I think I found it. this (ArrayIndexOutOfBoundsException crash) only happens when there is no optifine,
if I run falsetweaks + falsepatternlib + unimixins + hbm + optifine, then this crash doesn't happen
Most likely, I didn’t notice this because I always run game with optifine

VERY strange, now falsetweaks crashes (ArrayIndexOutOfBoundsException) every time I create a world with hbm, but I didn't change the version of any of these mods.
Crash report: https://pastebin.com/mHjELG46

to reproduce:

1. Download falsetweaks, falsepatternlib, unimixins, and hbm
2. create a new world (preferably a super-flat one, as hbm structures appear there more often)
3. get a crash (?)

I was able to reproduce it (BufferOverflowException) without doing anything, it just crashed: https://pastebin.com/uBxLhmP2

hi, what is HBM?

Hbms Nuclear Tech Mod

Send the entire fml_client_latest.log file

1. BufferOverflowException: Unfortunately, I didn’t have any logs saved, all that’s left in the instance folder are .gz archives, but there’s nothing useful in them at all, there’s only 15 lines. As soon as I can reproduce it I will save it and post it

2. ArrayIndexOutOfBoundsException: fixed in 2.7.0 Preview 1

Does this still happen in 3.5.x?