Hopper: java.lang.ClassCastException: aol cannot be cast to amv

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-14544/

Crash:

java.lang.ClassCastException: aol cannot be cast to amv
	at amw.<init>(SourceFile:33)
	at amv.a(SourceFile:372)
	at amv.a(SourceFile:334)
	at adq.a(SourceFile:395)
	at abv.f(SourceFile:306)
	at aiq.a(SourceFile:384)
	at aiq.a(SourceFile:513)
	at agh.a(SourceFile:392)
	at ais.a(SourceFile:29)
	at aim.a(SourceFile:72)
	at aes.a(SourceFile:425)
	at jq.a(SourceFile:168)
	at adq.a(SourceFile:726)
	at jq.c(SourceFile:105)
	at jq.d(SourceFile:116)
	at abv.e(SourceFile:289)
	at ack.<init>(SourceFile:32)
	at abv.a(SourceFile:2241)
	at re.a(SourceFile:78)
	at re.a(SourceFile:82)
	at ql.c(SourceFile:41)
	at ps.a(SourceFile:91)
	at of.bh(SourceFile:410)
	at oe.c(SourceFile:1289)
	at of.c(SourceFile:292)
	at tl.c(SourceFile:24)
	at tv.c(SourceFile:141)
	at oe.l_(SourceFile:1176)
	at of.l_(SourceFile:169)
	at tl.l_(SourceFile:29)
	at tv.l_(SourceFile:197)
	at abv.a(SourceFile:1349)
	at jr.a(SourceFile:479)
	at abv.g(SourceFile:1327)

The following is the first clean report made public about this crash:

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

Time: 8/6/13 5:36 PM
Description: Ticking entity

java.lang.ClassCastException: aqr cannot be cast to amv
	at amw.<init>(SourceFile:33)
	at amv.a(SourceFile:372)
	at amv.a(SourceFile:334)
	at adq.a(SourceFile:395)
	at abv.f(SourceFile:306)
	at aiq.a(SourceFile:384)
	at aiq.a(SourceFile:513)
	at agh.a(SourceFile:392)
	at ais.a(SourceFile:29)
	at aim.a(SourceFile:72)
	at aes.a(SourceFile:425)
	at jq.a(SourceFile:168)
	at adq.a(SourceFile:726)
	at jq.c(SourceFile:105)
	at jq.d(SourceFile:116)
	at abv.e(SourceFile:289)
	at ack.<init>(SourceFile:32)
	at abv.a(SourceFile:2241)
	at re.a(SourceFile:78)
	at re.a(SourceFile:82)
	at ql.c(SourceFile:41)
	at ps.a(SourceFile:91)
	at of.bh(SourceFile:410)
	at oe.c(SourceFile:1289)
	at of.c(SourceFile:292)
	at tl.c(SourceFile:24)
	at tv.c(SourceFile:141)
	at oe.l_(SourceFile:1176)
	at of.l_(SourceFile:169)
	at tl.l_(SourceFile:29)
	at tv.l_(SourceFile:197)
	at abv.a(SourceFile:1349)
	at jr.a(SourceFile:479)
	at abv.g(SourceFile:1327)
	at abv.h(SourceFile:1234)
	at jr.h(SourceFile:364)
	at net.minecraft.server.MinecraftServer.t(SourceFile:470)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bkw.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hh.run(SourceFile:582)


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

-- Head --
Stacktrace:
	at amw.<init>(SourceFile:33)
	at amv.a(SourceFile:372)
	at amv.a(SourceFile:334)
	at adq.a(SourceFile:395)
	at abv.f(SourceFile:306)
	at aiq.a(SourceFile:384)
	at aiq.a(SourceFile:513)
	at agh.a(SourceFile:392)
	at ais.a(SourceFile:29)
	at aim.a(SourceFile:72)
	at aes.a(SourceFile:425)
	at jq.a(SourceFile:168)
	at adq.a(SourceFile:726)
	at jq.c(SourceFile:105)
	at jq.d(SourceFile:116)
	at abv.e(SourceFile:289)
	at ack.<init>(SourceFile:32)
	at abv.a(SourceFile:2241)
	at re.a(SourceFile:78)
	at re.a(SourceFile:82)
	at ql.c(SourceFile:41)
	at ps.a(SourceFile:91)
	at of.bh(SourceFile:410)
	at oe.c(SourceFile:1289)
	at of.c(SourceFile:292)
	at tl.c(SourceFile:24)
	at tv.c(SourceFile:141)
	at oe.l_(SourceFile:1176)
	at of.l_(SourceFile:169)
	at tl.l_(SourceFile:29)
	at tv.l_(SourceFile:197)
	at abv.a(SourceFile:1349)
	at jr.a(SourceFile:479)
	at abv.g(SourceFile:1327)

-- Entity being ticked --
Details:
	Entity Type: Zombie (tv)
	Entity ID: 422
	Entity Name: Zombie
	Entity's Exact location: -989.50, 38.00, 1115.50
	Entity's Block location: World: (-990,38,1115), Chunk: (at 2,2,11 in -62,69; contains blocks -992,0,1104 to -977,255,1119), Region: (-2,2; contains chunks -64,64 to -33,95, blocks -1024,0,1024 to -513,255,1535)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at abv.h(SourceFile:1234)
	at jr.h(SourceFile:364)

-- Affected level --
Details:
	Level name: herobrine
	All players: 1 total; [ju['amu23p'/211, l='herobrine', x=-1056.71, y=64.00, z=1204.93]]
	Chunk stats: ServerChunkCache: 1091 Drop: 0
	Level seed: 106834569
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (156,64,248), Chunk: (at 12,4,8 in 9,15; contains blocks 144,0,240 to 159,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 24644 game time, 24644 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 18043 (now: true), thunder time: 65487 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.t(SourceFile:470)
	at net.minecraft.server.MinecraftServer.s(SourceFile:405)
	at bkw.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:339)
	at hh.run(SourceFile:582)

-- System Details --
Details:
	Minecraft Version: 1.6.2
	Operating System: Mac OS X (x86_64) version 10.6.8
	Java Version: 1.6.0_39, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 120218408 bytes (114 MB) / 273055744 bytes (260 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 5973 (334488 bytes; 0 MB) allocated, 4720 (264320 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1935 (108360 bytes; 0 MB) allocated, 1519 (85064 bytes; 0 MB) used
	Player Count: 1 / 8; [ju['amu23p'/211, l='herobrine', x=-1056.71, y=64.00, z=1204.93]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-14544/1024435/