Versions (Be specific, do not write "latest"):

• Champions: 2.0.1.13
• Forge: 36.2.34

Observed Behavior:

Sincerest apologies ahead of time as this crash is extremely rare due to my hardware, but I was not able to get it to reproduce at all, with and without all the unnecessary mods.

Randomly I had found this concurrent modification exception thanks to forge's night config whilst champions froze the client trying to load its default config due to an NPE on the config thread that did not close the client with it. it's possible the lockup was entirely caused by some sort of conflict changing values of things rather than purely the config thread itself, causing a domino effect. however because this crashlog shows absolutely no other listeners or mixins besides optifine, I felt it possible it is an actual issue with champions although extremely rare considering it requires quite specific threading circumstances.

crash found on Kaleidio's Battle Pack 4.3.7 dev branch, it caused the window to suddenly stop responding. may or may not be possible in 4.3.6, cannot deduce conflicting mods besides what is shown in pathtrace in crashlog.

Expected Behavior:

Not sure what to expect here, or what mods I should remove. Opening this issue anyway to keep track for my own personal development and a heads up just in case something is broken in night config as of the forge version above. maybe something weird between forge versions?

Steps to Reproduce:

crashes starting a new singleplayer world. extremely random, cannot give an exact list of steps.

Crash Log: https://pastebin.com/BiY1sNnh