Affected Mod Versions:

(Please list other mods and their versions if you feel they are relevant to this issue. i.e. Biomes O' Plenty)
mod list is already in crashlog.txt

• Forge version:
  forge-1.12.2-14.23.4.2709-universal.jar
• RTG version:
  RTG-1.12.2-6.1.0.0-alpha.1.jar (built by June 22, 2018 via 1.12.2-update github version)

Issue Description:

(Please provide screenshots if neccessary/possible. Images can be dragged & dropped into this window.)
Error show "java.lang.NoSuchFieldError: polar_chasm" while loading minecraft.

Steps to reproduce the issue: (If it's easily reproducible.)

1. Start the game.
2. waiting for the game appear to main menu (but it didn't happen)

Extra Information:

crash-2018-06-22_17.47.43-client.txt
fml-client-latest.log

There is no 1.12 release. There is no working branch for 1.12. Please stop building from source and opening issues, 1.12 is not ready yet.