Steps to reproduce:
1. Use Sethbling's add attribute filter in MCEdit
2. Hover over the tool with your mouse
3. This happens...
---- Minecraft Crash Report ----
// Ooh. Shiny.
Time: 20/07/13 10:01 PM
Description: Ticking player
java.lang.IllegalArgumentException: Modifier name cannot be empty
at org.apache.commons.lang3.Validate.notEmpty(Validate.java:398)
at os.<init>(SourceFile:31)
at to.a(SourceFile:94)
at yd.D(SourceFile:580)
at oe.l_(SourceFile:1170)
at ue.l_(SourceFile:203)
at ju.h(SourceFile:180)
at jz.a(SourceFile:190)
at et.a(SourceFile:136)
at cm.b(SourceFile:64)
at jz.e(SourceFile:60)
at kc.b(SourceFile:37)
at bkz.b(SourceFile:84)
at net.minecraft.server.MinecraftServer.t(SourceFile:488)
at net.minecraft.server.MinecraftServer.s(SourceFile:405)
at bkw.s(SourceFile:124)
at net.minecraft.server.MinecraftServer.run(SourceFile:339)
at hh.run(SourceFile:582)
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 os.<init>(SourceFile:31)
at to.a(SourceFile:94)
at yd.D(SourceFile:580)
at oe.l_(SourceFile:1170)
at ue.l_(SourceFile:203)
-- Player being ticked --
Details:
Entity Type: null (ju)
Entity ID: 1125820
Entity Name: Jragon14
Entity's Exact location: 341.05, 56.00, 1462.58
Entity's Block location: World: (341,56,1462), Chunk: (at 5,3,6 in 21,91; contains blocks 336,0,1456 to 351,255,1471), Region: (0,2; contains chunks 0,64 to 31,95, blocks 0,0,1024 to 511,255,1535)
Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
at ju.h(SourceFile:180)
at jz.a(SourceFile:190)
at et.a(SourceFile:136)
at cm.b(SourceFile:64)
at jz.e(SourceFile:60)
-- Ticking connection --
Details:
Connection: jz@a82d8e
Stacktrace:
at kc.b(SourceFile:37)
at bkz.b(SourceFile:84)
at net.minecraft.server.MinecraftServer.t(SourceFile:488)
at net.minecraft.server.MinecraftServer.s(SourceFile:405)
at bkw.s(SourceFile:124)
at net.minecraft.server.MinecraftServer.run(SourceFile:339)
at hh.run(SourceFile:582)
-- System Details --
Details:
Minecraft Version: 1.6.2
Operating System: Windows 7 (x86) version 6.1
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 182131520 bytes (173 MB) / 316821504 bytes (302 MB) up to 1037959168 bytes (989 MB)
JVM Flags: 1 total; -Xmx1G
AABB Pool Size: 332 (18592 bytes; 0 MB) allocated, 321 (17976 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
Profiler Position: N/A (disabled)
Vec3 Pool Size: 13 (728 bytes; 0 MB) allocated, 13 (728 bytes; 0 MB) used
Player Count: 1 / 8; [ju['Jragon14'/1125820, l='Computers', x=341.05, y=56.00, z=1462.58]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.
Linked issues
Comments

Duplicate of MC-19629, please use the search function to see if your bug has already been submitted. Currently over 58% of tickets are being resolved as duplicate.
Based on a crash report provided in this issue, I believe with high certainty that this report may be a duplicate of MC-24767. You can view all information known about this specific crash at MCX-903.