Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at axm.a(SourceFile:558)
	at awy.a(SourceFile:168)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 19/09/13 17:02
Description: Rendering screen

java.lang.NullPointerException
	at axm.a(SourceFile:558)
	at awy.a(SourceFile:168)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)
	at bfe.b(SourceFile:718)
	at atv.S(SourceFile:686)
	at atv.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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

-- Head --
Stacktrace:
	at axm.a(SourceFile:558)
	at awy.a(SourceFile:168)
	at axp.a(SourceFile:31)
	at axm.a(SourceFile:529)

-- Screen render details --
Details:
	Screen name: axm
	Mouse location: Scaled: (278, 205). Absolute: (835, 346)
	Screen size: Scaled: (427, 321). Absolute: (1280, 962). Scale factor of 3

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdi['arthurwilliams'/85, l='MpServer', x=-5763.96, y=114.77, z=85.51]]
	Chunk stats: MultiplayerChunkCache: 441
	Level seed: 0
	Level generator: ID 02 - largeBiomes, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-109,64,-4), Chunk: (at 3,4,12 in -7,-1; contains blocks -112,0,-16 to -97,255,-1), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Level time: 356125 game time, 4779 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: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 88 total; [ro['Bat'/548, l='MpServer', x=-5711.82, y=32.48, z=97.71], ro['Bat'/549, l='MpServer', x=-5701.39, y=45.90, z=110.63], ro['Bat'/257, l='MpServer', x=-5762.45, y=20.01, z=59.60], ry['Pig'/261, l='MpServer', x=-5787.72, y=64.00, z=63.19], ss['item.item.dyePowder.black'/812, l='MpServer', x=-5822.69, y=55.13, z=54.75], ro['Bat'/574, l='MpServer', x=-5687.54, y=23.80, z=54.15], ry['Pig'/265, l='MpServer', x=-5790.53, y=60.00, z=106.53], ro['Bat'/1125, l='MpServer', x=-5764.18, y=15.31, z=87.38], ro['Bat'/1122, l='MpServer', x=-5759.65, y=14.55, z=85.84], ro['Bat'/1033, l='MpServer', x=-5759.44, y=32.70, z=156.50], ro['Bat'/1034, l='MpServer', x=-5747.47, y=33.98, z=151.25], ry['Pig'/77, l='MpServer', x=-5812.75, y=63.00, z=69.91], ry['Pig'/78, l='MpServer', x=-5813.47, y=65.00, z=79.53], ro['Bat'/1030, l='MpServer', x=-5756.16, y=31.00, z=144.72], ro['Bat'/1031, l='MpServer', x=-5756.41, y=32.60, z=155.00], ub['Villager'/84, l='MpServer', x=-5787.31, y=70.00, z=75.53], ub['Villager'/81, l='MpServer', x=-5795.59, y=63.00, z=70.50], ub['Villager'/80, l='MpServer', x=-5787.56, y=64.00, z=66.56], ro['Bat'/1044, l='MpServer', x=-5720.25, y=25.00, z=100.50], uh['arrow'/373, l='MpServer', x=-5762.88, y=70.94, z=100.97], uh['arrow'/375, l='MpServer', x=-5762.94, y=70.94, z=100.50], uh['arrow'/374, l='MpServer', x=-5762.28, y=70.94, z=100.50], ss['item.item.potato'/381, l='MpServer', x=-5763.78, y=71.13, z=98.81], uh['arrow'/377, l='MpServer', x=-5762.63, y=70.94, z=100.19], uh['arrow'/376, l='MpServer', x=-5762.72, y=70.94, z=100.63], ro['Bat'/590, l='MpServer', x=-5691.66, y=37.71, z=100.16], uh['arrow'/379, l='MpServer', x=-5764.41, y=70.56, z=101.63], uh['arrow'/378, l='MpServer', x=-5762.97, y=70.94, z=100.75], ss['item.item.dyePowder.black'/357, l='MpServer', x=-5786.31, y=57.13, z=127.13], ry['Pig'/359, l='MpServer', x=-5790.75, y=59.00, z=133.53], ry['Pig'/360, l='MpServer', x=-5760.06, y=64.00, z=62.31], ry['Pig'/361, l='MpServer', x=-5772.72, y=64.00, z=57.13], sc['Squid'/844, l='MpServer', x=-5793.47, y=53.00, z=129.50], ry['Pig'/138, l='MpServer', x=-5841.53, y=64.00, z=107.31], ry['Pig'/414, l='MpServer', x=-5758.59, y=64.00, z=63.09], ry['Pig'/415, l='MpServer', x=-5756.63, y=64.00, z=64.22], sc['Squid'/412, l='MpServer', x=-5761.31, y=61.38, z=151.50], ss['item.item.dyePowder.black'/153, l='MpServer', x=-5827.50, y=55.13, z=56.28], ss['item.item.dyePowder.black'/154, l='MpServer', x=-5826.63, y=56.13, z=57.88], ry['Pig'/398, l='MpServer', x=-5774.53, y=64.00, z=96.53], ry['Pig'/158, l='MpServer', x=-5838.22, y=63.00, z=59.84], rs['Dinnerbone'/159, l='MpServer', x=-5834.06, y=64.00, z=84.09], ss['item.item.dyePowder.black'/149, l='MpServer', x=-5825.56, y=53.13, z=44.84], ss['item.item.dyePowder.black'/150, l='MpServer', x=-5826.13, y=52.13, z=44.13], ry['Pig'/151, l='MpServer', x=-5834.91, y=61.00, z=62.75], ry['Pig'/440, l='MpServer', x=-5750.63, y=71.00, z=105.22], uh['arrow'/435, l='MpServer', x=-5752.00, y=71.25, z=101.50], ss['item.item.porkchopRaw'/436, l='MpServer', x=-5758.56, y=70.13, z=98.16], ss['item.item.potato'/437, l='MpServer', x=-5758.00, y=71.13, z=96.19], ss['item.item.porkchopRaw'/438, l='MpServer', x=-5758.88, y=70.13, z=100.88], ry['Pig'/164, l='MpServer', x=-5828.50, y=63.00, z=119.59], ss['item.item.dyePowder.black'/186, l='MpServer', x=-5823.78, y=57.13, z=45.94], ry['Pig'/187, l='MpServer', x=-5817.03, y=63.00, z=44.97], ss['item.item.dyePowder.black'/188, l='MpServer', x=-5822.13, y=55.13, z=53.94], ry['Pig'/417, l='MpServer', x=-5754.72, y=64.00, z=56.19], ry['Pig'/416, l='MpServer', x=-5750.31, y=67.00, z=71.50], bdi['arthurwilliams'/85, l='MpServer', x=-5763.96, y=114.77, z=85.51], sy['entity.MinecartRideable.name'/195, l='MpServer', x=-5821.50, y=68.50, z=101.44], ry['Pig'/216, l='MpServer', x=-5797.16, y=63.00, z=67.25], ry['Pig'/218, l='MpServer', x=-5796.09, y=63.00, z=65.78], ry['Pig'/213, l='MpServer', x=-5804.16, y=64.00, z=47.06], ry['Pig'/214, l='MpServer', x=-5795.41, y=64.00, z=44.16], ry['Pig'/215, l='MpServer', x=-5794.38, y=64.00, z=45.38], ry['Pig'/239, l='MpServer', x=-5795.84, y=51.00, z=117.59], ry['Pig'/238, l='MpServer', x=-5794.50, y=53.00, z=118.56], ry['Pig'/237, l='MpServer', x=-5796.53, y=48.00, z=124.31], ry['Pig'/236, l='MpServer', x=-5796.53, y=46.00, z=122.47], ry['Pig'/235, l='MpServer', x=-5796.47, y=46.00, z=122.53], ry['Pig'/234, l='MpServer', x=-5796.47, y=46.00, z=122.53], ry['Pig'/233, l='MpServer', x=-5796.53, y=46.00, z=122.47], ry['Pig'/232, l='MpServer', x=-5796.53, y=46.00, z=122.47], ro['Bat'/1195, l='MpServer', x=-5738.84, y=30.85, z=84.66], ro['Bat'/1193, l='MpServer', x=-5736.25, y=28.98, z=92.69], ry['Pig'/497, l='MpServer', x=-5747.75, y=71.00, z=106.59], ro['Bat'/1197, l='MpServer', x=-5746.50, y=21.85, z=73.72], ry['Pig'/225, l='MpServer', x=-5803.47, y=57.00, z=108.47], ro['Bat'/1196, l='MpServer', x=-5742.16, y=21.85, z=68.03], ry['Pig'/224, l='MpServer', x=-5804.44, y=63.00, z=91.25], ry['Pig'/254, l='MpServer', x=-5790.50, y=64.00, z=45.38], ry['Pig'/255, l='MpServer', x=-5779.47, y=64.00, z=47.53], ro['Bat'/1200, l='MpServer', x=-5694.63, y=50.00, z=7.28], ro['Bat'/252, l='MpServer', x=-5768.73, y=47.76, z=9.25], sc['Squid'/975, l='MpServer', x=-5826.34, y=53.00, z=54.50], ss['item.item.seeds'/488, l='MpServer', x=-5740.19, y=72.13, z=90.06], sc['Squid'/972, l='MpServer', x=-5824.63, y=53.00, z=45.50], ss['item.item.wheat'/487, l='MpServer', x=-5739.91, y=72.13, z=89.38], ry['Pig'/240, l='MpServer', x=-5806.56, y=53.00, z=123.41], ry['Pig'/241, l='MpServer', x=-5796.53, y=60.00, z=135.19]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bdd.a(SourceFile:284)
	at atv.b(SourceFile:1761)
	at atv.d(SourceFile:628)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	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: 229500296 bytes (218 MB) / 482803712 bytes (460 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 1474 (82544 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 71
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: GeForce GT 640/PCIe/SSE2 GL version 4.3.0, NVIDIA Corporation
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 490 (27440 bytes; 0 MB) allocated, 27 (1512 bytes; 0 MB) used