Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at nj.a(SourceFile:89)
	at of.aJ(SourceFile:384)
	at of.y(SourceFile:214)
	at nn.l_(SourceFile:278)
	at of.l_(SourceFile:1149)
	at uf.l_(SourceFile:203)

---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 9/19/13 4:23 PM
Description: Ticking player

java.lang.NullPointerException
	at nj.a(SourceFile:89)
	at of.aJ(SourceFile:384)
	at of.y(SourceFile:214)
	at nn.l_(SourceFile:278)
	at of.l_(SourceFile:1149)
	at uf.l_(SourceFile:203)
	at jv.h(SourceFile:185)
	at ka.a(SourceFile:190)
	at eu.a(SourceFile:136)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)


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

-- Head --
Stacktrace:
	at nj.a(SourceFile:89)
	at of.aJ(SourceFile:384)
	at of.y(SourceFile:214)
	at nn.l_(SourceFile:278)
	at of.l_(SourceFile:1149)
	at uf.l_(SourceFile:203)

-- Player being ticked --
Details:
	Entity Type: null (jv)
	Entity ID: 40
	Entity Name: tohaa010
	Entity's Exact location: -660.18, 4.00, 952.17
	Entity's Block location: World: (-661,4,952), Chunk: (at 11,0,8 in -42,59; contains blocks -672,0,944 to -657,255,959), Region: (-2,1; contains chunks -64,32 to -33,63, blocks -1024,0,512 to -513,255,1023)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at jv.h(SourceFile:185)
	at ka.a(SourceFile:190)
	at eu.a(SourceFile:136)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)

-- Ticking connection --
Details:
	Connection: ka@1c05d2f
Stacktrace:
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows Vista (x86) version 6.0
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 204751200 bytes (195 MB) / 358625280 bytes (342 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 665 (37240 bytes; 0 MB) allocated, 605 (33880 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: 72 (4032 bytes; 0 MB) allocated, 72 (4032 bytes; 0 MB) used
	Player Count: 1 / 8; [jv['tohaa010'/40, l='bar', x=-660.18, y=4.00, z=952.17]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.