Hopper: java.lang.NullPointerException at ams.<init>(SourceFile:33)

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-30555/

Crash:

java.lang.NullPointerException
	at ams.<init>(SourceFile:33)
	at amr.a(SourceFile:372)
	at amr.a(SourceFile:334)
	at adm.a(SourceFile:395)
	at abr.f(SourceFile:307)
	at aim.a(SourceFile:384)
	at aim.a(SourceFile:513)
	at agd.a(SourceFile:392)
	at aio.a(SourceFile:29)
	at aii.a(SourceFile:76)
	at aeo.a(SourceFile:425)
	at jo.a(SourceFile:168)
	at adm.a(SourceFile:732)
	at jo.c(SourceFile:105)
	at jn.<init>(SourceFile:29)
	at jm.a(SourceFile:208)
	at jm.a(SourceFile:240)
	at hk.a(SourceFile:138)
	at hk.c(SourceFile:185)
	at hk.a(SourceFile:82)
	at bkr.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bko.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hf.run(SourceFile:582)

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

---- Minecraft Crash Report ----
// This is a token for 1 free hug. Redeem at your nearest Mojangsta: [~~HUG~~]

Time: 05.08.13 21:02
Description: Exception in server tick loop

java.lang.NullPointerException
	at ams.<init>(SourceFile:33)
	at amr.a(SourceFile:372)
	at amr.a(SourceFile:334)
	at adm.a(SourceFile:395)
	at abr.f(SourceFile:307)
	at aim.a(SourceFile:384)
	at aim.a(SourceFile:513)
	at agd.a(SourceFile:392)
	at aio.a(SourceFile:29)
	at aii.a(SourceFile:76)
	at aeo.a(SourceFile:425)
	at jo.a(SourceFile:168)
	at adm.a(SourceFile:732)
	at jo.c(SourceFile:105)
	at jn.<init>(SourceFile:29)
	at jm.a(SourceFile:208)
	at jm.a(SourceFile:240)
	at hk.a(SourceFile:138)
	at hk.c(SourceFile:185)
	at hk.a(SourceFile:82)
	at bkr.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bko.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hf.run(SourceFile:582)


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

-- System Details --
Details:
	Minecraft Version: 1.6.1
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 181013480 bytes (172 MB) / 318468096 bytes (303 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 1103 (61768 bytes; 0 MB) allocated, 1045 (58520 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 147 (8232 bytes; 0 MB) allocated, 147 (8232 bytes; 0 MB) used
	Player Count: 1 / 8; [js['Rudi_88'/10552, l='FreLu', x=-920,94, y=71,25, z=112,79]]
	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-30555/748826/