java.lang.NoClassDefFoundError

Crash: http://pastebin.com/XJs9ds0M
Code: https://gist.github.com/MrIbby/aa46d412f93908b2b181

[Atybot]

Probably related to your compiler and
, new IItemState() { blah blah }

and wtf...

Minecraft Version: 16w03a<===

blah blah

Launched Version: 15w51b<===