First off, as I entered a sludgepit, my server crashed and experienced this error:

http://pastebin.com/dztHdUTE

Secondly, this crash keeps happening for me in MCPC, I don't know if its connected to biomes o plenty or not, but, I'll post it here just incase it is.

http://pastebin.com/AMxJn8DJ

I'll look into the first error, however the second one is invalid so long as it's from MCPC+ as it is not "officially" supported by us.