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-465751/

Crash:

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rv.<init>(SourceFile:29)
	at wv.a(SourceFile:94)
	at abp.D(SourceFile:594)
	at rh.h(SourceFile:1199)
	at xl.h(SourceFile:240)

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

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

Time: 10/25/13 12:01 PM
Description: Ticking player

java.lang.IllegalArgumentException: Modifier name cannot be empty
	at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rv.<init>(SourceFile:29)
	at wv.a(SourceFile:94)
	at abp.D(SourceFile:594)
	at rh.h(SourceFile:1199)
	at xl.h(SourceFile:240)
	at mm.i(SourceFile:207)
	at mx.a(SourceFile:209)
	at ir.a(SourceFile:137)
	at it.a(SourceFile:20)
	at ef.a(SourceFile:164)
	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 org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
	at rv.<init>(SourceFile:29)
	at wv.a(SourceFile:94)
	at abp.D(SourceFile:594)
	at rh.h(SourceFile:1199)
	at xl.h(SourceFile:240)

-- Player being ticked --
Details:
	Entity Type: null (mm)
	Entity ID: 8
	Entity Name: texelelf
	Entity's Exact location: 4.71, 57.00, -69.30
	Entity's Block location: World: (4,57,-70), Chunk: (at 4,3,10 in 0,-5; contains blocks 0,0,-80 to 15,255,-65), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
	Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
	at mm.i(SourceFile:207)
	at mx.a(SourceFile:209)
	at ir.a(SourceFile:137)
	at it.a(SourceFile:20)
	at ef.a(SourceFile:164)

-- Ticking connection --
Details:
	Connection: ef@389a99d2
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: 1.7.0_40, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 173925248 bytes (165 MB) / 434634752 bytes (414 MB) up to 2863661056 bytes (2731 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3G
	AABB Pool Size: 120 (6720 bytes; 0 MB) allocated, 120 (6720 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 9 (504 bytes; 0 MB) allocated, 9 (504 bytes; 0 MB) used
	Player Count: 1 / 8; [mm['texelelf'/8, l='Test_World', x=4.71, y=57.00, z=-69.30]]
	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-465751/21439894/