Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at ou.a(SourceFile:523)
	at kg.a(SourceFile:677)
	at ou.c(SourceFile:493)
	at zj.b(SourceFile:79)
	at yx.b(SourceFile:116)
	at uw.o(SourceFile:290)
	at kg.o(SourceFile:654)
	at uw.o_(SourceFile:175)

---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 9/5/13 9:08 PM
Description: Ticking player

java.lang.NullPointerException
	at ou.a(SourceFile:523)
	at kg.a(SourceFile:677)
	at ou.c(SourceFile:493)
	at zj.b(SourceFile:79)
	at yx.b(SourceFile:116)
	at uw.o(SourceFile:290)
	at kg.o(SourceFile:654)
	at uw.o_(SourceFile:175)
	at kg.h(SourceFile:192)
	at kl.a(SourceFile:195)
	at fe.a(SourceFile:136)
	at cx.b(SourceFile:64)
	at kl.e(SourceFile:63)
	at ko.b(SourceFile:37)
	at bnj.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)


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

-- Head --
Stacktrace:
	at ou.a(SourceFile:523)
	at kg.a(SourceFile:677)
	at ou.c(SourceFile:493)
	at zj.b(SourceFile:79)
	at yx.b(SourceFile:116)
	at uw.o(SourceFile:290)
	at kg.o(SourceFile:654)
	at uw.o_(SourceFile:175)

-- Player being ticked --
Details:
	Entity Type: null (kg)
	Entity ID: 61139
	Entity Name: SquidofCubes
	Entity's Exact location: 696.77, 4.00, -123.19
	Entity's Block location: World: (696,4,-124), Chunk: (at 8,0,4 in 43,-8; contains blocks 688,0,-128 to 703,255,-113), Region: (1,-1; contains chunks 32,-32 to 63,-1, blocks 512,0,-512 to 1023,255,-1)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at kg.h(SourceFile:192)
	at kl.a(SourceFile:195)
	at fe.a(SourceFile:136)
	at cx.b(SourceFile:64)
	at kl.e(SourceFile:63)

-- Ticking connection --
Details:
	Connection: kl@56a2b626
Stacktrace:
	at ko.b(SourceFile:37)
	at bnj.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)

-- System Details --
Details:
	Minecraft Version: 13w36a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_07, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 160305472 bytes (152 MB) / 357302272 bytes (340 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 431 (24136 bytes; 0 MB) allocated, 377 (21112 bytes; 0 MB) used
	Suspicious classes: [com.ibm.icu.text.ArabicShapingException], [gnu.trove.TIntCollection], [gnu.trove.impl.HashFunctions, PrimeFinder], [gnu.trove.impl.hash.THash, TPrimitiveHash, TIntIntHash], [gnu.trove.iterator.TIterator, TAdvancingIterator, TIntIntIterator], [gnu.trove.map.TIntIntMap], [gnu.trove.map.hash.TIntIntHashMap], [gnu.trove.procedure.TIntIntProcedure], [gnu.trove.set.TIntSet]
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 53 (2968 bytes; 0 MB) allocated, 39 (2184 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['SquidofCubes'/61139, l='towers', x=696.77, y=4.00, z=-123.19]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.