java.lang.Error - Server Crash

The server randomly crashes, I've attached the most recent crash report below.

Time: 25/10/15 17:20
Description: Watching Server

java.lang.Error
	at rn.d(SourceFile:676)
	at rw.g(SourceFile:1426)
	at rw.n(SourceFile:1709)
	at rx.n(SourceFile:473)
	at rk.n(SourceFile:134)
	at vr.n(SourceFile:41)
	at vz.n(SourceFile:119)
	at rw.m(SourceFile:1542)
	at rx.m(SourceFile:265)
	at ahk.a(SourceFile:1481)
	at lq.a(SourceFile:719)
	at ahk.g(SourceFile:1459)
	at ahk.k(SourceFile:1349)
	at lq.k(SourceFile:552)
	at net.minecraft.server.MinecraftServer.D(SourceFile:618)
	at lb.D(SourceFile:314)
	at net.minecraft.server.MinecraftServer.C(SourceFile:546)
	at net.minecraft.server.MinecraftServer.run(SourceFile:450)
	at java.lang.Thread.run(Thread.java:745)