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

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-2388/

Crash:

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 zg.a(SourceFile:68)
	at yd.a(SourceFile:102)
	at jv.a(SourceFile:255)
	at jz.a(SourceFile:350)
	at gj.a(SourceFile:58)
	at cm.b(SourceFile:64)
	at jz.e(SourceFile:60)

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

---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 8/4/13 6:32 PM
Description: Ticking memory connection

java.lang.NullPointerException
	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 zg.a(SourceFile:68)
	at yd.a(SourceFile:102)
	at jv.a(SourceFile:255)
	at jz.a(SourceFile:350)
	at gj.a(SourceFile:58)
	at cm.b(SourceFile:64)
	at jz.e(SourceFile:60)
	at kc.b(SourceFile:37)
	at bkz.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	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 zg.a(SourceFile:68)
	at yd.a(SourceFile:102)
	at jv.a(SourceFile:255)
	at jz.a(SourceFile:350)
	at gj.a(SourceFile:58)
	at cm.b(SourceFile:64)
	at jz.e(SourceFile:60)

-- Ticking connection --
Details:
	Connection: jz@122cae2
Stacktrace:
	at kc.b(SourceFile:37)
	at bkz.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:488)
	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: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 153261016 bytes (146 MB) / 421081088 bytes (401 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 649 (36344 bytes; 0 MB) allocated, 517 (28952 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 125 (7000 bytes; 0 MB) allocated, 97 (5432 bytes; 0 MB) used
	Player Count: 1 / 8; [ju['Trevor8460'/40, l='New World', x=-5.17, y=237.00, z=342.57]]
	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-2388/602565/