Hopper: java.lang.NullPointerException

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-247539/

Crash:

java.lang.NullPointerException
	at auo.f(SourceFile:202)
	at jh.m(SourceFile:692)
	at net.minecraft.server.MinecraftServer.a(SourceFile:873)
	at bou.a(SourceFile:195)
	at np.b(SourceFile:92)
	at net.minecraft.server.MinecraftServer.t(SourceFile:439)
	at bou.t(SourceFile:121)
	at net.minecraft.server.MinecraftServer.run(SourceFile:346)
	at jc.run(SourceFile:582)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Don't be sad. I'll do better next time, I promise!

Time: 9/27/13 3:12 PM
Description: Exception in server tick loop

java.lang.NullPointerException
	at auo.f(SourceFile:202)
	at jh.m(SourceFile:692)
	at net.minecraft.server.MinecraftServer.a(SourceFile:873)
	at bou.a(SourceFile:195)
	at np.b(SourceFile:92)
	at net.minecraft.server.MinecraftServer.t(SourceFile:439)
	at bou.t(SourceFile:121)
	at net.minecraft.server.MinecraftServer.run(SourceFile:346)
	at jc.run(SourceFile:582)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
	Minecraft Version: 13w39b
	Operating System: Mac OS X (x86_64) version 10.8.5
	Java Version: 1.6.0_51, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 67711416 bytes (64 MB) / 172634112 bytes (164 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 6669 (373464 bytes; 0 MB) allocated, 5979 (334824 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 2379 (133224 bytes; 0 MB) allocated, 1963 (109928 bytes; 0 MB) used
	Player Count: 1 / 8; [kq['jedeming'/202, l='free', x=-555.42, y=70.05, z=469.92]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-247539/14733778/