Hopper: java.lang.ClassCastException: wu cannot be cast to bah

java.lang.ClassCastException: wu cannot be cast to bah
	at baf.a(SourceFile:176)
	at azr.b(SourceFile:515)
	at baf.b(SourceFile:412)
	at ayr.d(SourceFile:137)
	at baf.d(SourceFile:489)
	at ayr.m(SourceFile:109)

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 05/09/13 20:36
Description: Updating screen events

java.lang.ClassCastException: wu cannot be cast to bah
	at baf.a(SourceFile:176)
	at azr.b(SourceFile:515)
	at baf.b(SourceFile:412)
	at ayr.d(SourceFile:137)
	at baf.d(SourceFile:489)
	at ayr.m(SourceFile:109)
	at avx.m(SourceFile:1202)
	at avx.V(SourceFile:686)
	at avx.e(SourceFile:642)
	at net.minecraft.client.main.Main.main(SourceFile:103)


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

-- Head --
Stacktrace:
	at baf.a(SourceFile:176)
	at azr.b(SourceFile:515)
	at baf.b(SourceFile:412)
	at ayr.d(SourceFile:137)
	at baf.d(SourceFile:489)
	at ayr.m(SourceFile:109)

-- Affected screen --
Details:
	Screen name: baf

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bfg['Jazzy_Clarinet'/55, l='MpServer', x=308.97, y=75.12, z=947.25]]
	Chunk stats: MultiplayerChunkCache: 318, 318
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (0,64,252), Chunk: (at 0,4,12 in 0,15; contains blocks 0,0,240 to 15,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 21572 game time, 21572 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: 56 total; [sd['Bat'/91218, l='MpServer', x=249.50, y=31.10, z=965.25], sd['Bat'/91259, l='MpServer', x=360.50, y=38.62, z=938.17], sd['Bat'/91260, l='MpServer', x=362.60, y=36.93, z=937.53], sd['Bat'/91261, l='MpServer', x=355.63, y=41.10, z=933.25], bfg['Jazzy_Clarinet'/55, l='MpServer', x=193.48, y=-279.59, z=89.69], sd['Bat'/91682, l='MpServer', x=273.61, y=31.30, z=918.26], tj['item.item.seeds'/91653, l='MpServer', x=263.81, y=63.13, z=892.59], sd['Bat'/91718, l='MpServer', x=277.03, y=35.00, z=921.66], sd['Bat'/91715, l='MpServer', x=275.59, y=35.48, z=922.28], sd['Bat'/91714, l='MpServer', x=275.78, y=35.00, z=921.47], sg['Cow'/90323, l='MpServer', x=242.50, y=64.00, z=996.50], sg['Cow'/90322, l='MpServer', x=244.19, y=64.00, z=992.50], sg['Cow'/90321, l='MpServer', x=245.53, y=64.00, z=992.50], sg['Cow'/90320, l='MpServer', x=246.50, y=65.00, z=995.50], sg['Cow'/90327, l='MpServer', x=335.97, y=63.00, z=986.09], sg['Cow'/90326, l='MpServer', x=331.50, y=63.00, z=992.75], sg['Cow'/90325, l='MpServer', x=339.88, y=63.00, z=990.91], sg['Cow'/90324, l='MpServer', x=337.50, y=63.00, z=996.50], sg['Cow'/90517, l='MpServer', x=342.78, y=63.00, z=975.50], sg['Cow'/90516, l='MpServer', x=343.50, y=63.00, z=977.50], sg['Cow'/90519, l='MpServer', x=341.50, y=63.00, z=978.50], sg['Cow'/90518, l='MpServer', x=341.19, y=63.00, z=975.50], sg['Cow'/90816, l='MpServer', x=269.34, y=70.00, z=939.22], sg['Cow'/90817, l='MpServer', x=261.59, y=69.00, z=958.63], sg['Cow'/90815, l='MpServer', x=262.50, y=69.00, z=947.50], sg['Cow'/90814, l='MpServer', x=265.78, y=70.00, z=951.50], sg['Cow'/90770, l='MpServer', x=333.97, y=64.00, z=950.09], sg['Cow'/90769, l='MpServer', x=323.94, y=65.00, z=958.06], sg['Cow'/90768, l='MpServer', x=327.50, y=64.00, z=955.22], sg['Cow'/90767, l='MpServer', x=319.59, y=65.00, z=951.25], bfg['Jazzy_Clarinet'/55, l='MpServer', x=308.97, y=75.12, z=947.25], sd['Bat'/91117, l='MpServer', x=237.45, y=46.72, z=979.15], sg['Cow'/91084, l='MpServer', x=303.50, y=63.00, z=873.50], sg['Cow'/91085, l='MpServer', x=304.50, y=63.00, z=878.50], sg['Cow'/91083, l='MpServer', x=296.50, y=64.00, z=872.50], sg['Cow'/90991, l='MpServer', x=265.63, y=62.00, z=892.47], sg['Cow'/90990, l='MpServer', x=264.47, y=62.00, z=893.53], sg['Cow'/90989, l='MpServer', x=270.03, y=63.00, z=904.00], sg['Cow'/90988, l='MpServer', x=227.72, y=64.00, z=896.25], su['Wolf'/90998, l='MpServer', x=286.06, y=66.00, z=892.53], su['Wolf'/90999, l='MpServer', x=280.38, y=63.00, z=894.69], sg['Cow'/90996, l='MpServer', x=284.94, y=66.00, z=892.56], su['Wolf'/90997, l='MpServer', x=281.69, y=63.00, z=892.88], sg['Cow'/90994, l='MpServer', x=292.50, y=64.00, z=890.50], sg['Cow'/90995, l='MpServer', x=292.28, y=66.00, z=898.78], sg['Cow'/90992, l='MpServer', x=275.78, y=64.00, z=891.19], sg['Cow'/90993, l='MpServer', x=294.16, y=65.00, z=898.09], su['Wolf'/91000, l='MpServer', x=280.09, y=63.00, z=893.25], tl['entity.MinecartChest.name'/90930, l='MpServer', x=286.50, y=31.50, z=906.50], tj['item.tile.rail'/90931, l='MpServer', x=322.88, y=36.13, z=908.34], tj['item.tile.rail'/90934, l='MpServer', x=320.13, y=36.13, z=903.88], tj['item.tile.rail'/90932, l='MpServer', x=321.16, y=36.13, z=903.81], sg['Cow'/90883, l='MpServer', x=254.81, y=69.00, z=927.16], sg['Cow'/90885, l='MpServer', x=252.22, y=71.00, z=928.50], sg['Cow'/90884, l='MpServer', x=251.50, y=70.00, z=930.50], sg['Cow'/90886, l='MpServer', x=253.59, y=70.00, z=928.75]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bfb.a(SourceFile:285)
	at avx.b(SourceFile:1813)
	at avx.e(SourceFile:651)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 13w36a
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_11, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 64944088 bytes (61 MB) / 274759680 bytes (262 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 747 (41832 bytes; 0 MB) allocated, 2 (112 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
	Launched Version: 13w36a
	LWJGL: 2.9.0
	OpenGL: ATI Radeon HD 5400 Series GL version 4.0.10151 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: English (UK)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1687 (94472 bytes; 0 MB) allocated, 15 (840 bytes; 0 MB) used