Hopper: java.lang.IllegalArgumentException: Cannot get property bci{name=extended, clazz=class java.lang.Boolean, values=[true, false]} as it does not exist!

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-1685210/

Crash:

java.lang.IllegalArgumentException: Cannot get property bci{name=extended, clazz=class java.lang.Boolean, values=[true, false]} as it does not exist!
	at bbw.b(SourceFile:91)
	at bbk.b(SourceFile:66)
	at bcw.a(SourceFile:505)
	at apm.a(SourceFile:274)
	at aph.a(SourceFile:199)
	at qg.a(SourceFile:809)
	at acn.bI(SourceFile:209)
	at wz.bC(SourceFile:468)
	at wy.l(SourceFile:1425)
	at wz.l(SourceFile:328)
	at aeo.l(SourceFile:39)
	at acn.l(SourceFile:153)
	at wy.j(SourceFile:1293)
	at wz.j(SourceFile:207)
	at aeo.j(SourceFile:44)
	at apm.a(SourceFile:1370)
	at qg.a(SourceFile:572)
	at apm.g(SourceFile:1348)

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

---- Minecraft Crash Report ----
// Ouch. That hurt :(

Time: 7/9/14 11:23 PM
Description: Ticking entity

java.lang.IllegalArgumentException: Cannot get property bci{name=extended, clazz=class java.lang.Boolean, values=[true, false]} as it does not exist!
	at bbw.b(SourceFile:91)
	at bbk.b(SourceFile:66)
	at bcw.a(SourceFile:505)
	at apm.a(SourceFile:274)
	at aph.a(SourceFile:199)
	at qg.a(SourceFile:809)
	at acn.bI(SourceFile:209)
	at wz.bC(SourceFile:468)
	at wy.l(SourceFile:1425)
	at wz.l(SourceFile:328)
	at aeo.l(SourceFile:39)
	at acn.l(SourceFile:153)
	at wy.j(SourceFile:1293)
	at wz.j(SourceFile:207)
	at aeo.j(SourceFile:44)
	at apm.a(SourceFile:1370)
	at qg.a(SourceFile:572)
	at apm.g(SourceFile:1348)
	at apm.i(SourceFile:1253)
	at qg.i(SourceFile:450)
	at net.minecraft.server.MinecraftServer.x(SourceFile:586)
	at net.minecraft.server.MinecraftServer.w(SourceFile:510)
	at cwg.w(SourceFile:132)
	at net.minecraft.server.MinecraftServer.run(SourceFile:426)
	at java.lang.Thread.run(Unknown Source)


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

-- Head --
Stacktrace:
	at bbw.b(SourceFile:91)
	at bbk.b(SourceFile:66)
	at bcw.a(SourceFile:505)
	at apm.a(SourceFile:274)
	at aph.a(SourceFile:199)
	at qg.a(SourceFile:809)
	at acn.bI(SourceFile:209)
	at wz.bC(SourceFile:468)
	at wy.l(SourceFile:1425)
	at wz.l(SourceFile:328)
	at aeo.l(SourceFile:39)
	at acn.l(SourceFile:153)
	at wy.j(SourceFile:1293)
	at wz.j(SourceFile:207)
	at aeo.j(SourceFile:44)
	at apm.a(SourceFile:1370)
	at qg.a(SourceFile:572)
	at apm.g(SourceFile:1348)

-- Entity being ticked --
Details:
	Entity Type: WitherBoss (acn)
	Entity ID: 7442027
	Entity Name: Wither
	Entity's Exact location: -5.50, 121.00, -21.50
	Entity's Block location: -6.00,121.00,-22.00 - World: (-6,121,-22), Chunk: (at 10,7,10 in -1,-2; contains blocks -16,0,-32 to -1,255,-17), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Entity's Momentum: 0.00, -0.05, 0.00
	Entity's Rider: ~~ERROR~~ NullPointerException: null
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at apm.i(SourceFile:1253)
	at qg.i(SourceFile:450)

-- Affected level --
Details:
	Level name: New World
	All players: 1 total; [qj['ericfussell'/646574, l='New World', x=-0.30, y=120.71, z=-18.30]]
	Chunk stats: ServerChunkCache: 303 Drop: 0
	Level seed: -5622329398227369455
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: 0.00,0.00,0.00 - World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 0 game time, 0 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at net.minecraft.server.MinecraftServer.x(SourceFile:586)
	at net.minecraft.server.MinecraftServer.w(SourceFile:510)
	at cwg.w(SourceFile:132)
	at net.minecraft.server.MinecraftServer.run(SourceFile:426)
	at java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
	Minecraft Version: 14w28a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 3376065928 bytes (3219 MB) / 4277665792 bytes (4079 MB) up to 4277665792 bytes (4079 MB)
	JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4096M -Xms4096M
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 99
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [qj['ericfussell'/646574, l='New World', x=-0.30, y=120.71, z=-18.30]]
	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-1685210/69255205/