14w28a crashes when loading World

---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 09.07.14 17:56
Description: Exception ticking world

java.lang.IllegalArgumentException: Cannot get property bcl{name=age, clazz=class java.lang.Integer, values=[0, 1, 2, 3, 4, 5, 6, 7]} as it does not exist!
	at bbw.b(SourceFile:91)
	at ayt.b(SourceFile:127)
	at ayt.c(SourceFile:69)
	at ary.b(SourceFile:416)
	at qg.h(SourceFile:373)
	at qg.c(SourceFile:199)
	at net.minecraft.server.MinecraftServer.x(SourceFile:578)
	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 ayt.b(SourceFile:127)
	at ayt.c(SourceFile:69)
	at ary.b(SourceFile:416)
	at qg.h(SourceFile:373)
	at qg.c(SourceFile:199)

-- Affected level --
Details:
	Level name: World II
	All players: 1 total; [qj['LuxiKeks'/661, l='World II', x=311,25, y=63,00, z=216,60]]
	Chunk stats: ServerChunkCache: 693 Drop: 0
	Level seed: 8287910561556456512
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: 306,00,69,00,268,00 - World: (306,69,268), Chunk: (at 2,4,12 in 19,16; contains blocks 304,0,256 to 319,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 30796267 game time, 29075613 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 156610 (now: false), thunder time: 84647 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.x(SourceFile:578)
	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: 1.8.0_05, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 801194736 bytes (764 MB) / 1188560896 bytes (1133 MB) up to 1789919232 bytes (1707 MB)
	JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -Xmn1G
	IntCache: cache: 9, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [qj['LuxiKeks'/661, l='World II', x=311,25, y=63,00, z=216,60]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.