(1.19)
Optifabric seems to have incompatibilities when it is intalled together with Slight GUI Modifications and Optifabric (and Optifine). Only the combination of those 3 mods crashes the game. No other combinations. See the following:

Optifabric (and Optifine ) + Borderless Mining = working
Optifabric (and Optifine ) + Slight GUI Modifications = working
Borderless Mining + Slight GUI Modifications = working
Borderless Mining + Optifabric (and Optifine ) + Slight GUI Modifications = crash

Shedaniel, the dev of Slight GUI Modification closed my issue to his mod with the comment "I don't care about optifine", so maybe there's a possible fix by Borderless Mining?

Already did that. Thanks for the quick response, I hope it's Optifabric's fault

As mentioned in #43 and #42, please report these issues to Optifabric.