Index 256 out of bounds for length 129

[mitelk03]

when i try to load the modpack Blightfall. i get the issue
Failure message: Quark (quark) has failed to load correctly
java.lang.ArrayIndexOutOfBoundsException: Index 256 out of bounds for length 129
i am not sure what that means. apperently there are 256 items in an array of only 129? or it is trying to find array item 256 but there is only 129 in the array, not sure which. I am still learning java.
crash-2025-02-12_19.29.00-fml.txt

[brisingraerowing]

According to the FastUtil dev, this is caused by multiple threads accessing the collection simultaneously. There's some mod being dumb with threads on game startup.