Please help!! I'm planning on release for this pack soon!!
The script is here: pastebin.com
I'm having trouble finding the error, and I've been working on this pack for over a year. Please help!!
I took a look at the crash report, try removing OptiFine.
"Mantle Environment: DO NOT REPORT THIS CRASH! Unsupported mods in environment: optifine"
I've had optifine in for months, as well as Mantle. It has never caused any problems before. :/ I'll try it though.
Edit: I found the issue - I had an outdated version of optifine. Whoops.
Maybe there is problem in the mod loader try to use the recommended FML version of the minecraft version that the mod is using