So i first issued the crash over at better combat. Which i got the reply '"Just Leveling" is performing mixin on Better Combat, meaning it alters the code of Better Combat, leading to a crash.
Mixins towards other mods are completely unsafe, and not supported at all.' So now i'm here with the crash report and latest log.

Crash Report:
crash-2023-10-31_23.34.06-client.txt

Latest Log:
latest.log

same Problem here