Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at zg.a(SourceFile:333)
	at vd.k(SourceFile:203)
	at vf.e(SourceFile:386)
	at bhz.e(SourceFile:201)
	at pd.h(SourceFile:1198)
	at vf.h(SourceFile:206)
	at bgf.h(SourceFile:49)
	at add.a(SourceFile:1372)
	at add.g(SourceFile:1350)

---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 20/09/13 16:18
Description: Ticking entity

java.lang.NullPointerException
	at zg.a(SourceFile:333)
	at vd.k(SourceFile:203)
	at vf.e(SourceFile:386)
	at bhz.e(SourceFile:201)
	at pd.h(SourceFile:1198)
	at vf.h(SourceFile:206)
	at bgf.h(SourceFile:49)
	at add.a(SourceFile:1372)
	at add.g(SourceFile:1350)
	at add.h(SourceFile:1257)
	at awo.o(SourceFile:1484)
	at awo.aa(SourceFile:730)
	at awo.e(SourceFile:681)
	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 zg.a(SourceFile:333)
	at vd.k(SourceFile:203)
	at vf.e(SourceFile:386)
	at bhz.e(SourceFile:201)
	at pd.h(SourceFile:1198)
	at vf.h(SourceFile:206)
	at bgf.h(SourceFile:49)
	at add.a(SourceFile:1372)
	at add.g(SourceFile:1350)

-- Entity being ticked --
Details:
	Entity Type: null (bgf)
	Entity ID: 28076
	Entity Name: Feadraco
	Entity's Exact location: 353,78, 81,62, 72,19
	Entity's Block location: World: (353,81,72), Chunk: (at 1,5,8 in 22,4; contains blocks 352,0,64 to 367,255,79), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0,00, 0,00, 0,00
Stacktrace:
	at add.h(SourceFile:1257)

-- Affected level --
Details:
	Level name: MpServer
	All players: 2 total; [bgf['Feadraco'/28076, l='MpServer', x=353,78, y=81,62, z=72,19], bia['ulventod'/353, l='MpServer', x=356,13, y=80,00, z=66,50]]
	Chunk stats: MultiplayerChunkCache: 15, 15
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (301,64,214), Chunk: (at 13,4,6 in 18,13; contains blocks 288,0,208 to 303,255,223), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 2605140 game time, 2605140 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: true), thunder time: 0 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: ~~ERROR~~ NullPointerException: null
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bga.a(SourceFile:294)
	at awo.b(SourceFile:1872)
	at awo.e(SourceFile:690)
	at net.minecraft.client.main.Main.main(SourceFile:104)

-- System Details --
Details:
	Minecraft Version: 13w38a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_17, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 166810672 bytes (159 MB) / 374669312 bytes (357 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 15961 (893816 bytes; 0 MB) allocated, 5 (280 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 13w38a
	LWJGL: 2.9.0
	OpenGL: ATI Radeon HD 4800 Series GL version 3.3.11672 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: Français (CA)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 67 (3752 bytes; 0 MB) allocated, 18 (1008 bytes; 0 MB) used