Hopper: java.lang.ClassCastException: asm cannot be cast to ary

java.lang.ClassCastException: asm cannot be cast to ary
	at ank.g_(SourceFile:246)
	at ank.a(SourceFile:236)
	at jw.a(SourceFile:247)
	at ka.a(SourceFile:352)
	at gk.a(SourceFile:58)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)

---- Minecraft Crash Report ----
// Shall we play a game?

Time: 9/19/13 5:49 PM
Description: Ticking memory connection

java.lang.ClassCastException: asm cannot be cast to ary
	at ank.g_(SourceFile:246)
	at ank.a(SourceFile:236)
	at jw.a(SourceFile:247)
	at ka.a(SourceFile:352)
	at gk.a(SourceFile:58)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)


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

-- Head --
Stacktrace:
	at ank.g_(SourceFile:246)
	at ank.a(SourceFile:236)
	at jw.a(SourceFile:247)
	at ka.a(SourceFile:352)
	at gk.a(SourceFile:58)
	at cn.b(SourceFile:64)
	at ka.e(SourceFile:60)

-- Ticking connection --
Details:
	Connection: ka@424187ef
Stacktrace:
	at kd.b(SourceFile:37)
	at blc.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:489)
	at net.minecraft.server.MinecraftServer.s(SourceFile:406)
	at bkz.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:340)
	at hi.run(SourceFile:583)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_09, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 166172232 bytes (158 MB) / 372047872 bytes (354 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 4129 (231224 bytes; 0 MB) allocated, 3013 (168728 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: 972 (54432 bytes; 0 MB) allocated, 746 (41776 bytes; 0 MB) used
	Player Count: 1 / 8; [jv['bsmith3417'/624, l='Rise of the Rebellion', x=1493.63, y=94.00, z=1152.11]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.