Description: Tesselating block in world java.lang.ClassCastException: ats cannot be cast to atk

Doing some mass cloning when this happens, I think it has something to do with the flower pots?

Save of a reproducible event can be sent on request, can't be made public since it's a WIP custom map.

Minecraft Crash Report ----
// I just don't know what went wrong 😞

Time: 14/03/14 10:27 PM
Description: Tesselating block in world

java.lang.ClassCastException: ats cannot be cast to atk
at bux.a(SourceFile:62)
at bux.a(SourceFile:21)
at btz.b(SourceFile:950)
at bta.a(SourceFile:163)
at btm.a(SourceFile:1403)
at btf.a(SourceFile:1097)
at btf.b(SourceFile:935)
at bfr.ai(SourceFile:828)
at bfr.f(SourceFile:755)
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 bux.a(SourceFile:62)
at bux.a(SourceFile:21)

– Block being tesselated –
Details:
Block type: ID #140 (tile.flowerPot // aou)
Block data value: 0 / 0x0 / 0b0000
Block location: World: (293,237,43), Chunk: (at 5,14,11 in 18,2; contains blocks 288,0,32 to 303,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Stacktrace:
at btz.b(SourceFile:950)
at bta.a(SourceFile:163)

– Chunk being rebuilt –
Details:
Renderchunk location: 288, 224, 32
Stacktrace:
at btm.a(SourceFile:1403)
at btf.a(SourceFile:1097)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bsv['Jigarbov'/44, l='MpServer', x=284.65, y=238.41, z=47.76]]
Chunk stats: MultiplayerChunkCache: 841, 841
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: -252.00,237.00,-11.00 - World: (-252,237,-11), Chunk: (at 4,14,5 in -16,-1; contains blocks -256,0,-16 to -241,255,-1), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 17859230 game time, 1000 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: 11 total; [za['item.tile.woolCarpet.lightBlue'/2368, l='MpServer', x=305.06, y=239.00, z=30.44], za['item.item.skull.char'/2369, l='MpServer', x=308.41, y=237.00, z=31.78], za['item.item.skull.skeleton'/2078, l='MpServer', x=276.56, y=236.00, z=49.19], za['item.item.sign'/2992, l='MpServer', x=281.22, y=236.00, z=55.50], za['item.tile.flower2.houstonia'/2993, l='MpServer', x=282.97, y=236.00, z=50.81], bsv['Jigarbov'/44, l='MpServer', x=284.65, y=238.41, z=47.76], za['item.item.skull.char'/2356, l='MpServer', x=314.53, y=236.00, z=15.50], za['item.item.sign'/53, l='MpServer', x=294.41, y=236.00, z=31.69], za['item.item.sign'/3391, l='MpServer', x=295.53, y=236.00, z=31.66], za['item.tile.woolCarpet.lightBlue'/2367, l='MpServer', x=306.53, y=237.00, z=32.00], za['item.tile.woolCarpet.lightBlue'/2366, l='MpServer', x=302.44, y=236.00, z=33.44]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bqr.a(SourceFile:308)
at bfr.b(SourceFile:2069)
at bfr.f(SourceFile:764)
at net.minecraft.client.main.Main.main(SourceFile:121)

– System Details –
Details:
Minecraft Version: 14w11b
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_11, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 247587248 bytes (236 MB) / 1049362432 bytes (1000 MB) up to 1049362432 bytes (1000 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 14w11b
LWJGL: 2.9.1
OpenGL: AMD Radeon R9 200 Series GL version 4.3.12618 Compatibility Profile Context 13.251.0.0, ATI Technologies Inc.
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)