Hopper: java.lang.ClassCastException: atf cannot be cast to aoc

java.lang.ClassCastException: atf cannot be cast to aoc
	at bsx.a(SourceFile:1255)
	at bsu.a(SourceFile:39)
	at bsv.a(SourceFile:915)
	at bsv.a(SourceFile:870)
	at bvj.a(SourceFile:73)
	at bvj.a(SourceFile:27)

---- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 16:35 06/03/14
Description: Rendering Block Entity

java.lang.ClassCastException: atf cannot be cast to aoc
	at bsx.a(SourceFile:1255)
	at bsu.a(SourceFile:39)
	at bsv.a(SourceFile:915)
	at bsv.a(SourceFile:870)
	at bvj.a(SourceFile:73)
	at bvj.a(SourceFile:27)
	at bvd.a(SourceFile:105)
	at bvd.a(SourceFile:97)
	at bsi.a(SourceFile:479)
	at bsb.a(SourceFile:1150)
	at bsb.b(SourceFile:935)
	at ben.ai(SourceFile:827)
	at ben.f(SourceFile:754)
	at net.minecraft.client.main.Main.main(SourceFile:121)


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

-- Head --
Stacktrace:
	at bsx.a(SourceFile:1255)
	at bsu.a(SourceFile:39)
	at bsv.a(SourceFile:915)
	at bsv.a(SourceFile:870)
	at bvj.a(SourceFile:73)
	at bvj.a(SourceFile:27)

-- Block Entity Details --
Details:
	Name: Piston // atg
	Block type: ID #36 (tile.null // atf)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (817,66,197), Chunk: (at 1,4,5 in 51,12; contains blocks 816,0,192 to 831,255,207), Region: (1,0; contains chunks 32,0 to 63,31, blocks 512,0,0 to 1023,255,511)
	Actual block type: ID #36 (tile.null // atf)
	Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
	at bvd.a(SourceFile:105)
	at bvd.a(SourceFile:97)
	at bsi.a(SourceFile:479)
	at bsb.a(SourceFile:1150)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [brr['yaniv_fly'/162, l='MpServer', x=817.30, y=63.00, z=196.57]]
	Chunk stats: MultiplayerChunkCache: 289, 289
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: 60.00,64.00,252.00 - World: (60,64,252), Chunk: (at 12,4,12 in 3,15; contains blocks 48,0,240 to 63,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 628280 game time, 17253 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: 76 total; [aao['Skeleton'/2989, l='MpServer', x=754.50, y=27.00, z=265.50], xt['Bat'/2853, l='MpServer', x=738.84, y=21.45, z=233.84], aao['Skeleton'/2991, l='MpServer', x=750.50, y=27.00, z=263.50], aao['Skeleton'/2990, l='MpServer', x=750.50, y=27.00, z=262.50], ze['container.minecart'/278, l='MpServer', x=852.50, y=18.50, z=142.50], yd['Pig'/277, l='MpServer', x=853.88, y=67.00, z=116.00], yd['Pig'/276, l='MpServer', x=859.50, y=66.00, z=117.28], yd['Pig'/280, l='MpServer', x=857.06, y=64.00, z=129.69], ye['Sheep'/287, l='MpServer', x=861.97, y=64.00, z=270.47], ye['Sheep'/286, l='MpServer', x=860.84, y=64.00, z=253.72], ye['Sheep'/285, l='MpServer', x=854.06, y=63.00, z=243.91], ye['Sheep'/258, l='MpServer', x=836.81, y=63.00, z=163.66], ze['container.minecart'/256, l='MpServer', x=831.50, y=22.50, z=130.50], ye['Sheep'/257, l='MpServer', x=824.72, y=63.00, z=143.19], uk['Painting'/262, l='MpServer', x=830.97, y=68.00, z=227.00], aav['Spider'/2728, l='MpServer', x=853.28, y=28.00, z=146.66], uk['Painting'/261, l='MpServer', x=830.97, y=68.00, z=230.00], aba['Zombie'/2727, l='MpServer', x=853.69, y=28.00, z=144.28], ze['container.minecart'/267, l='MpServer', x=833.50, y=23.50, z=143.50], aao['Skeleton'/2992, l='MpServer', x=752.50, y=27.00, z=264.50], aao['Skeleton'/2603, l='MpServer', x=876.50, y=25.00, z=216.50], ze['container.minecart'/268, l='MpServer', x=845.50, y=23.50, z=128.50], yd['Pig'/269, l='MpServer', x=844.16, y=63.00, z=142.84], uk['Painting'/250, l='MpServer', x=808.03, y=68.00, z=227.00], uk['Painting'/249, l='MpServer', x=808.03, y=68.00, z=230.00], zs['The Creeper'/163, l='MpServer', x=824.56, y=63.00, z=194.56], aba['Zombie'/2591, l='MpServer', x=748.50, y=68.00, z=147.50], aba['Zombie'/164, l='MpServer', x=805.91, y=55.00, z=195.56], yd['Pig'/291, l='MpServer', x=868.09, y=64.00, z=115.00], brr['yaniv_fly'/162, l='MpServer', x=817.30, y=63.00, z=196.57], yd['Pig'/292, l='MpServer', x=871.59, y=64.00, z=142.25], xv['Chicken'/191, l='MpServer', x=740.66, y=66.00, z=161.50], ye['Sheep'/293, l='MpServer', x=866.34, y=63.00, z=233.84], ye['Sheep'/188, l='MpServer', x=750.00, y=65.00, z=118.09], ye['Sheep'/294, l='MpServer', x=875.91, y=64.00, z=240.91], ye['Sheep'/295, l='MpServer', x=877.91, y=64.00, z=260.97], xv['Chicken'/189, l='MpServer', x=747.53, y=68.00, z=158.31], ye['Sheep'/296, l='MpServer', x=879.63, y=64.00, z=259.84], uk['Painting'/262, l='MpServer', x=830.97, y=68.00, z=227.00], ye['Sheep'/297, l='MpServer', x=869.03, y=64.00, z=272.00], uk['Painting'/261, l='MpServer', x=830.97, y=68.00, z=230.00], ye['Sheep'/299, l='MpServer', x=897.78, y=65.00, z=227.56], ye['Sheep'/207, l='MpServer', x=756.78, y=64.00, z=191.22], ye['Sheep'/202, l='MpServer', x=749.25, y=54.00, z=240.44], ye['Sheep'/198, l='MpServer', x=745.34, y=64.00, z=226.81], zs['Creeper'/2925, l='MpServer', x=748.50, y=68.00, z=155.50], xv['Chicken'/192, l='MpServer', x=740.53, y=65.00, z=185.34], zs['Creeper'/2926, l='MpServer', x=749.50, y=68.00, z=155.50], xv['Chicken'/195, l='MpServer', x=740.38, y=62.46, z=209.41], zs['Creeper'/2927, l='MpServer', x=748.15, y=68.00, z=159.29], ye['Sheep'/220, l='MpServer', x=770.97, y=65.00, z=128.09], xv['Chicken'/221, l='MpServer', x=776.59, y=66.00, z=166.41], ye['Sheep'/222, l='MpServer', x=775.00, y=65.00, z=173.00], aba['Zombie'/2657, l='MpServer', x=839.50, y=22.00, z=129.50], ye['Sheep'/219, l='MpServer', x=773.09, y=65.00, z=116.75], ye['Sheep'/212, l='MpServer', x=764.13, y=63.00, z=252.53], ye['Sheep'/213, l='MpServer', x=759.25, y=63.00, z=260.34], ye['Sheep'/214, l='MpServer', x=759.00, y=64.00, z=243.97], ye['Sheep'/215, l='MpServer', x=758.03, y=63.00, z=260.41], ye['Sheep'/208, l='MpServer', x=763.22, y=64.00, z=216.28], ye['Sheep'/210, l='MpServer', x=755.19, y=64.00, z=238.84], ye['Sheep'/211, l='MpServer', x=760.13, y=64.00, z=224.09], ye['Sheep'/232, l='MpServer', x=786.00, y=64.00, z=147.00], aba['Zombie'/2768, l='MpServer', x=823.50, y=17.00, z=126.50], ye['Sheep'/230, l='MpServer', x=798.34, y=64.00, z=130.19], ze['container.minecart'/255, l='MpServer', x=824.50, y=17.00, z=133.88], aav['Spider'/2903, l='MpServer', x=798.19, y=63.00, z=259.93], uk['Painting'/250, l='MpServer', x=808.03, y=68.00, z=227.00], aba['Zombie'/2767, l='MpServer', x=826.50, y=17.00, z=131.50], aba['Zombie'/248, l='MpServer', x=815.54, y=56.00, z=196.15], aba['Zombie'/2766, l='MpServer', x=825.50, y=17.00, z=128.50], uk['Painting'/249, l='MpServer', x=808.03, y=68.00, z=230.00], zs['The Creeper'/247, l='MpServer', x=814.59, y=63.00, z=194.53], aav['Spider'/2904, l='MpServer', x=797.50, y=63.00, z=268.50], aba['Zombie'/245, l='MpServer', x=804.50, y=55.00, z=195.84], ye['Sheep'/242, l='MpServer', x=808.25, y=63.00, z=125.13]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bpn.a(SourceFile:308)
	at ben.b(SourceFile:2068)
	at ben.f(SourceFile:763)
	at net.minecraft.client.main.Main.main(SourceFile:121)

-- System Details --
Details:
	Minecraft Version: 14w10a
	Operating System: Windows 8 (x86) version 6.2
	Java Version: 1.7.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 83443752 bytes (79 MB) / 304226304 bytes (290 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 14w10a
	LWJGL: 2.9.1
	OpenGL: GeForce GT 220/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Anisotropic Filtering: Off (1)