Seems to be with WindowIconHandler.setWindowIcon. Occurs with no other mods, just forge.

Forge: 14.23.4.2711
Log: https://paste.ee/p/82LXe

I'm having the same problem. The game starts loading, and quickly fails with the same error as @comp500.

Log file: https://paste.ee/p/nehbq

The game works if I remove RandomPatches 1.5.0.0 and return to using the older RandomPatches 1.4.1.1.

Looks like I forgot to see if the vanilla icon worked during testing. This should be fixed in 1.12.2-1.5.0.1.

@comp500 amd @Zarepheth Please do not set an expiration limit on crash reports when posting them like this. Both of your crash reports are now expired and removed, meaning that I am unable to compare your issue with mine. Please either make sure that you set it to not expire on Paste.ee or you use gist.github.com to post crash reports (or a similar site)