Hopper: java.lang.IllegalArgumentException: Modifier name cannot be empty

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-72373/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pi.<init>(SourceFile:31)
	at ug.a(SourceFile:92)
	at yx.D(SourceFile:581)
	at ou.o_(SourceFile:1188)
	at uw.o_(SourceFile:204)

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

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 9/5/13 6:02 PM
Description: Ticking player

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pi.<init>(SourceFile:31)
	at ug.a(SourceFile:92)
	at yx.D(SourceFile:581)
	at ou.o_(SourceFile:1188)
	at uw.o_(SourceFile:204)
	at kg.h(SourceFile:192)
	at kl.a(SourceFile:195)
	at fe.a(SourceFile:136)
	at cx.b(SourceFile:64)
	at kl.e(SourceFile:63)
	at ko.b(SourceFile:37)
	at bnj.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)


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

-- Head --
Stacktrace:
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at pi.<init>(SourceFile:31)
	at ug.a(SourceFile:92)
	at yx.D(SourceFile:581)
	at ou.o_(SourceFile:1188)
	at uw.o_(SourceFile:204)

-- Player being ticked --
Details:
	Entity Type: null (kg)
	Entity ID: 55
	Entity Name: notslif
	Entity's Exact location: 270.50, 237.00, 43.53
	Entity's Block location: World: (270,237,43), Chunk: (at 14,14,11 in 16,2; contains blocks 256,0,32 to 271,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at kg.h(SourceFile:192)
	at kl.a(SourceFile:195)
	at fe.a(SourceFile:136)
	at cx.b(SourceFile:64)
	at kl.e(SourceFile:63)

-- Ticking connection --
Details:
	Connection: kl@1610d6ac
Stacktrace:
	at ko.b(SourceFile:37)
	at bnj.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bng.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hs.run(SourceFile:575)

-- System Details --
Details:
	Minecraft Version: 13w36a
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_11, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 155110136 bytes (147 MB) / 452919296 bytes (431 MB) up to 1908932608 bytes (1820 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G
	AABB Pool Size: 839 (46984 bytes; 0 MB) allocated, 839 (46984 bytes; 0 MB) used
	Suspicious classes: [com.ibm.icu.text.ArabicShapingException], [gnu.trove.TIntCollection], [gnu.trove.impl.HashFunctions, PrimeFinder], [gnu.trove.impl.hash.THash, TPrimitiveHash, TIntIntHash], [gnu.trove.iterator.TIterator, TAdvancingIterator, TIntIntIterator], [gnu.trove.map.TIntIntMap], [gnu.trove.map.hash.TIntIntHashMap], [gnu.trove.procedure.TIntIntProcedure], [gnu.trove.set.TIntSet]
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 72 (4032 bytes; 0 MB) allocated, 61 (3416 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['notslif'/55, l='Test', x=270.50, y=237.00, z=43.53]]
	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-72373/8195180/