Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at zh.a(SourceFile:331)
	at ve.k(SourceFile:203)
	at vg.e(SourceFile:385)
	at bib.e(SourceFile:201)
	at pe.h(SourceFile:1186)
	at vg.h(SourceFile:205)
	at bgh.h(SourceFile:49)
	at ade.a(SourceFile:1348)
	at ade.g(SourceFile:1326)

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 20.09.13 18:03
Description: Ticking entity

java.lang.NullPointerException
	at zh.a(SourceFile:331)
	at ve.k(SourceFile:203)
	at vg.e(SourceFile:385)
	at bib.e(SourceFile:201)
	at pe.h(SourceFile:1186)
	at vg.h(SourceFile:205)
	at bgh.h(SourceFile:49)
	at ade.a(SourceFile:1348)
	at ade.g(SourceFile:1326)
	at ade.h(SourceFile:1233)
	at awp.o(SourceFile:1485)
	at awp.aa(SourceFile:726)
	at awp.e(SourceFile:677)
	at net.minecraft.client.main.Main.main(SourceFile:104)


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

-- Head --
Stacktrace:
	at zh.a(SourceFile:331)
	at ve.k(SourceFile:203)
	at vg.e(SourceFile:385)
	at bib.e(SourceFile:201)
	at pe.h(SourceFile:1186)
	at vg.h(SourceFile:205)
	at bgh.h(SourceFile:49)
	at ade.a(SourceFile:1348)
	at ade.g(SourceFile:1326)

-- Entity being ticked --
Details:
	Entity Type: null (bgh)
	Entity ID: 19396
	Entity Name: MarcusEvensen
	Entity's Exact location: -478,37, 64,62, -176,11
	Entity's Block location: World: (-479,64,-177), Chunk: (at 1,4,15 in -30,-12; contains blocks -480,0,-192 to -465,255,-177), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Entity's Momentum: 0,00, 0,00, 0,00
Stacktrace:
	at ade.h(SourceFile:1233)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bgh['MarcusEvensen'/19396, l='MpServer', x=-478,37, y=64,62, z=-176,11]]
	Chunk stats: MultiplayerChunkCache: 0, 0
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-229,64,188), Chunk: (at 11,4,12 in -15,11; contains blocks -240,0,176 to -225,255,191), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 2185236 game time, 687293 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 1 total; [bgh['MarcusEvensen'/19396, l='MpServer', x=-478,37, y=64,62, z=-176,11]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bgc.a(SourceFile:297)
	at awp.b(SourceFile:1874)
	at awp.e(SourceFile:686)
	at net.minecraft.client.main.Main.main(SourceFile:104)

-- System Details --
Details:
	Minecraft Version: 13w38c
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 111084800 bytes (105 MB) / 177012736 bytes (168 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 659 (36904 bytes; 0 MB) allocated, 5 (280 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 13w38c
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics Family GL version 3.1.0 - Build 8.15.10.2372, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: [faithful32pack.zip]
	Current Language: English (UK)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 104 (5824 bytes; 0 MB) allocated, 11 (616 bytes; 0 MB) used