Forge version:
Twilight Forest version: 4.0.412
Link to crash log: (please use a paste site such as gist, do not attach the .txt or paste the log inline)

Crash report and Debug.log
Steps to reproduce:

1. apply shaders
   What I expected to happen:
   not have funky shader look
   What happened instead:
   funky shader look
   
   (happens with multiple different shaders)

Also this issue #1199 because the shaders cause this and I don't know what shaders did they use.

These are two separate issues, yes shaders are involved but it's two totally different sections of the game

i'm having the same issue. anyone figured out how to fix this problem client side yet?

This has always been an issue with shaders, shaders do not support custom sky boxes. Use a shader that doesnt affect the sky.
Also: duplicate #854