Hopper: java.lang.ClassCastException: ahm cannot be cast to ahq

java.lang.ClassCastException: ahm cannot be cast to ahq
	at ahr.<init>(SourceFile:33)
	at ahq.a(SourceFile:372)
	at ahq.b(SourceFile:334)
	at aoj.a(SourceFile:468)
	at afn.d(SourceFile:327)
	at atv.a(SourceFile:411)
	at atv.a(SourceFile:535)
	at ark.a(SourceFile:447)
	at atx.a(SourceFile:37)
	at atp.a(SourceFile:88)
	at apl.a(SourceFile:403)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:781)
	at mi.c(SourceFile:95)
	at mh.<init>(SourceFile:31)
	at mg.a(SourceFile:212)
	at mg.a(SourceFile:249)
	at ld.a(SourceFile:155)
	at ld.c(SourceFile:206)
	at ld.a(SourceFile:100)
	at nd.c(SourceFile:87)
	at nd.a(SourceFile:52)
	at ef.a(SourceFile:166)

---- Minecraft Crash Report ----
// Would you like a cupcake?

Time: 25.10.13 16:45
Description: Ticking memory connection

java.lang.ClassCastException: amh cannot be cast to ahq
	at ahr.<init>(SourceFile:33)
	at ahq.a(SourceFile:372)
	at ahq.b(SourceFile:334)
	at aoj.a(SourceFile:468)
	at afn.d(SourceFile:327)
	at atv.a(SourceFile:411)
	at atv.a(SourceFile:535)
	at ark.a(SourceFile:447)
	at atx.a(SourceFile:37)
	at atp.a(SourceFile:88)
	at apl.a(SourceFile:403)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:781)
	at mi.c(SourceFile:95)
	at mh.<init>(SourceFile:31)
	at mg.a(SourceFile:212)
	at mg.a(SourceFile:249)
	at ld.a(SourceFile:155)
	at ld.c(SourceFile:206)
	at ld.a(SourceFile:100)
	at nd.c(SourceFile:87)
	at nd.a(SourceFile:52)
	at ef.a(SourceFile:166)
	at ms.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	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 ahr.<init>(SourceFile:33)
	at ahq.a(SourceFile:372)
	at ahq.b(SourceFile:334)
	at aoj.a(SourceFile:468)
	at afn.d(SourceFile:327)
	at atv.a(SourceFile:411)
	at atv.a(SourceFile:535)
	at ark.a(SourceFile:447)
	at atx.a(SourceFile:37)
	at atp.a(SourceFile:88)
	at apl.a(SourceFile:403)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:781)
	at mi.c(SourceFile:95)
	at mh.<init>(SourceFile:31)
	at mg.a(SourceFile:212)
	at mg.a(SourceFile:249)
	at ld.a(SourceFile:155)
	at ld.c(SourceFile:206)
	at ld.a(SourceFile:100)
	at nd.c(SourceFile:87)
	at nd.a(SourceFile:52)
	at ef.a(SourceFile:166)

-- Ticking connection --
Details:
	Connection: ef@600f11bc
Stacktrace:
	at ms.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	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: Windows 7 (amd64) version 6.1
	Java Version: 1.6.0_26, Sun Microsystems Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Sun Microsystems Inc.
	Memory: 317658472 bytes (302 MB) / 451149824 bytes (430 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 2318 (129808 bytes; 0 MB) allocated, 2318 (129808 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 227 (12712 bytes; 0 MB) allocated, 227 (12712 bytes; 0 MB) used
	Player Count: 1 / 8; [mm['jowi98'/1070, l='petermagföhnwurst', x=972,54, y=69,70, z=602,30]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.