mcMMO Weird Errors

These errors started occuring only 3 days ago, not sure of the cause. They occur every so often, not always.

It has at net.minecraft.server.v1_7_R2.DedicatedServer.v(DedicatedServer.java:273) [spigot.jar:git-Spigot-1387] In there somewhere so i'm wondering is it a glitch with the server or mcMMO? Thanks!

Full Error in copy & paste: http://pastebin.com/7YK43pf8