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-398586/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rs.<init>(SourceFile:29)
	at ws.a(SourceFile:94)
	at abm.D(SourceFile:594)
	at re.h(SourceFile:1194)
	at xi.h(SourceFile:240)

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

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

Time: 20/10/13 17:18
Description: Ticking player

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rs.<init>(SourceFile:29)
	at ws.a(SourceFile:94)
	at abm.D(SourceFile:594)
	at re.h(SourceFile:1194)
	at xi.h(SourceFile:240)
	at ml.i(SourceFile:207)
	at mv.a(SourceFile:202)
	at iq.a(SourceFile:137)
	at iq.a(SourceFile:8)
	at el.a(SourceFile:145)
	at mr.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsb.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kx.run(SourceFile:617)


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 rs.<init>(SourceFile:29)
	at ws.a(SourceFile:94)
	at abm.D(SourceFile:594)
	at re.h(SourceFile:1194)
	at xi.h(SourceFile:240)

-- Player being ticked --
Details:
	Entity Type: null (ml)
	Entity ID: 5380476
	Entity Name: blabla180
	Entity's Exact location: 327.27, 56.00, 423.80
	Entity's Block location: World: (327,56,423), Chunk: (at 7,3,7 in 20,26; contains blocks 320,0,416 to 335,255,431), 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 ml.i(SourceFile:207)
	at mv.a(SourceFile:202)
	at iq.a(SourceFile:137)
	at iq.a(SourceFile:8)
	at el.a(SourceFile:145)

-- Ticking connection --
Details:
	Connection: el@6dbe9391
Stacktrace:
	at mr.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsb.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kx.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 13w42b
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_07, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 70911200 bytes (67 MB) / 774504448 bytes (738 MB) up to 3817799680 bytes (3640 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G
	AABB Pool Size: 90 (5040 bytes; 0 MB) allocated, 52 (2912 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 6 (336 bytes; 0 MB) allocated, 5 (280 bytes; 0 MB) used
	Player Count: 1 / 8; [ml['blabla180'/5380476, l='Redstone', x=327.27, y=56.00, z=423.80]]
	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-398586/19997677/