Hopper: java.lang.ClassCastException: any cannot be cast to anx

java.lang.ClassCastException: any cannot be cast to anx
	at akv.a(SourceFile:19)

---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 10/25/13 3:22 PM
Description: Exception while updating neighbours

java.lang.ClassCastException: any cannot be cast to anx
	at akv.a(SourceFile:19)
	at afn.e(SourceFile:480)
	at afn.d(SourceFile:462)
	at afn.c(SourceFile:428)
	at afn.d(SourceFile:337)
	at afn.f(SourceFile:390)
	at ajn.a(SourceFile:258)
	at afn.e(SourceFile:480)
	at afn.d(SourceFile:461)
	at afn.c(SourceFile:428)
	at afn.d(SourceFile:337)
	at afn.f(SourceFile:390)
	at ajn.a(SourceFile:201)
	at ajn.a(SourceFile:151)
	at mj.a(SourceFile:405)
	at mj.b(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:503)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)


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

-- Head --
Stacktrace:
	at akv.a(SourceFile:19)

-- Block being updated --
Details:
	Source block type: ID #51 (tile.fire // ajn)
	Block type: ID #25 (tile.musicBlock // akv)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (-43,35,-95), Chunk: (at 5,2,1 in -3,-6; contains blocks -48,0,-96 to -33,255,-81), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Stacktrace:
	at afn.e(SourceFile:480)
	at afn.d(SourceFile:462)
	at afn.c(SourceFile:428)
	at afn.d(SourceFile:337)
	at afn.f(SourceFile:390)
	at ajn.a(SourceFile:258)

-- Block being updated --
Details:
	Source block type: ID #35 (tile.cloth // aim)
	Block type: ID #51 (tile.fire // ajn)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (-43,35,-94), Chunk: (at 5,2,2 in -3,-6; contains blocks -48,0,-96 to -33,255,-81), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Stacktrace:
	at afn.e(SourceFile:480)
	at afn.d(SourceFile:461)
	at afn.c(SourceFile:428)
	at afn.d(SourceFile:337)
	at afn.f(SourceFile:390)
	at ajn.a(SourceFile:201)
	at ajn.a(SourceFile:151)

-- Block being ticked --
Details:
	Block type: ID #51 (tile.fire // ajn)
	Block data value: 4 / 0x4 / 0b0100
	Block location: World: (-42,34,-94), Chunk: (at 6,2,2 in -3,-6; contains blocks -48,0,-96 to -33,255,-81), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Stacktrace:
	at mj.a(SourceFile:405)
	at mj.b(SourceFile:134)

-- Affected level --
Details:
	Level name: Royal Palace
	All players: 1 total; [mm['klatimer18'/310, l='Royal Palace', x=-37.39, y=19.00, z=-125.46]]
	Chunk stats: ServerChunkCache: 778 Drop: 0
	Level seed: -1104976106
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (32,64,-4), Chunk: (at 0,4,12 in 2,-1; contains blocks 32,0,-16 to 47,255,-1), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
	Level time: 81259 game time, 81259 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 133410 (now: false), thunder time: 120551 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
	at net.minecraft.server.MinecraftServer.u(SourceFile:503)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Mac OS X (x86_64) version 10.9
	Java Version: 1.6.0_65, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 73597936 bytes (70 MB) / 185765888 bytes (177 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 1311 (73416 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 11, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 146 (8176 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Player Count: 1 / 8; [mm['klatimer18'/310, l='Royal Palace', x=-37.39, y=19.00, z=-125.46]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.