Hopper: java.lang.NullPointerException (SourceFile:33)

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-12844/

Crash:

java.lang.NullPointerException
	at amw.<init>(SourceFile:33)
	at amv.a(SourceFile:372)
	at amv.a(SourceFile:334)
	at adq.a(SourceFile:395)
	at abv.f(SourceFile:306)
	at aiq.a(SourceFile:384)
	at aiq.a(SourceFile:513)
	at agh.a(SourceFile:392)
	at ais.a(SourceFile:29)
	at aim.a(SourceFile:72)
	at aen.a(SourceFile:125)
	at jq.a(SourceFile:168)
	at adq.a(SourceFile:732)
	at jq.c(SourceFile:105)
	at jp.<init>(SourceFile:29)
	at jo.a(SourceFile:208)
	at jo.a(SourceFile:240)
	at hm.a(SourceFile:141)
	at hm.c(SourceFile:188)
	at hm.a(SourceFile:85)
	at bkz.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bkw.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hh.run(SourceFile:582)

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

---- Minecraft Crash Report ----
// My bad.

Time: 04/08/13 15:43
Description: Exception in server tick loop

java.lang.NullPointerException
	at amw.<init>(SourceFile:33)
	at amv.a(SourceFile:372)
	at amv.a(SourceFile:334)
	at adq.a(SourceFile:395)
	at abv.f(SourceFile:306)
	at aiq.a(SourceFile:384)
	at aiq.a(SourceFile:513)
	at agh.a(SourceFile:392)
	at ais.a(SourceFile:29)
	at aim.a(SourceFile:72)
	at aen.a(SourceFile:125)
	at jq.a(SourceFile:168)
	at adq.a(SourceFile:732)
	at jq.c(SourceFile:105)
	at jp.<init>(SourceFile:29)
	at jo.a(SourceFile:208)
	at jo.a(SourceFile:240)
	at hm.a(SourceFile:141)
	at hm.c(SourceFile:188)
	at hm.a(SourceFile:85)
	at bkz.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bkw.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hh.run(SourceFile:582)


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

-- System Details --
Details:
	Minecraft Version: 1.6.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_17, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 155903408 bytes (148 MB) / 349573120 bytes (333 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 227 (12712 bytes; 0 MB) allocated, 227 (12712 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 51 (2856 bytes; 0 MB) allocated, 51 (2856 bytes; 0 MB) used
	Player Count: 1 / 8; [ju['50mjack'/74, l='The walking dead', x=1536.07, y=21.77, z=-737.04]]
	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-12844/475116/