I know it's an ArmorPlus exception, but it doesn't crash and the error doesn't appear in the log without foamfix.

The game crashes on forge loading screen with foamfix enabled.

Crash report:
https://gist.github.com/CourtArtanis/83bff7a0e34e91a69c4c1f1a600b25cf

🤔

Could you try turning off model deduplication in the config?

Which entry is that, sir?
B:deduplicateModelBakers=true
or
B:deduplicate=true ?

Just turn off both.

That did the trick!

https://gist.github.com/CourtArtanis/532b3a49f34e695ee2250eba2b7493ad
The config as it is now for reference.

Ah, so it is a bug.

Eyy (At least the issue its not mine), but I'm curious to see what causes it.

Does the issue persist?

Mantle-1.12-1.3.2.24.jar
TConstruct-1.12.2-2.10.1.87.jar
armorplus-1.12.2-11.14.0.42.jar
thedragonlib-1.12.2-5.3.0.jar

plus FoamFix 0.10.2 and I could not reproduce it. Do I need additional mods?

Anyhow, could you try https://asie.pl/files/foamfix-0.10.3-test2-1.12.2-anarchy.jar ? I tried to blind-fix the issue.

Excellent, thanks!

0.10.3 released

Your Welcome Will go download the update now, Thanks For the Quick Update.

Asiekierka Im Currently having the same issue. im using:
foamfix-0.10.2.1.12.2.jar/foamfix-0.10.0-1.12.2.jar (tried both versions separately) Mantle-1.12-3.3.39.jar TConstruct-1.12.2-2.11.0.106.jar armorplus-1.12.2-11.13.0.40.jar
Currently getting the the same crash noted above.
I can Confirm that foamfix-0.10.3-test2-1.12.2-anarchy.jar did not crash with the armorplus and mantle same versions noted above. So the Blind Fix did work to resolve the issue.