Details:
Mod File: Quark-r2.4-283.jar
Failure message: Quark (quark) encountered an error during the complete event phase
java.lang.ArrayIndexOutOfBoundsException: -1
Mod Version: r2.4-283
Mod Issue URL: https://github.com/Vazkii/Quark
Exception message: java.lang.ArrayIndexOutOfBoundsException: -1

The really odd thing that I noticed is that this error does not happen everytime, just some of the time.

crash-2020-12-30_21.19.01-fml.txt

Got same thing, reported as
[1.16.4] CTD on game start
ticket. I suggest you to trie using charm 2.1.9

Also, happy new year ^_^

I experience the exact same thing, hopefully this gets fixed soon.

Same as #2767