Playing Elucent's newest custom pack, occasionally crash to desktop with this crash log:

http://pastebin.com/FkehiHUW

No idea how to create or reproduce this, just happens occasionally upon joining the server.

Maybe @immortaleeb knows what the problem is here.

Similar issue happened when slaying/hitting a zombie pigman in the overworld.

http://pastebin.com/ei9wCLxF

I'm not able to reproduce the crash, but the changes in the last commit could resolve your issues.
A new update with this change is coming soon.