Slabs can't be placed next to slabs

When placing a wooden slab next to a wooden slab, the game crashes.
Report submitted to Mojang.
Crash Report:

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

Time: 7/9/14 11:20 AM
Description: Unexpected error

java.lang.IllegalArgumentException: Cannot get property bcj{name=variant, clazz=class azb, values=[stone, sandstone, wood_old, cobblestone, brick, stone_brick, nether_brick, quartz]} as it does not exist!
at bbw.b(SourceFile:91)
at ami.a(SourceFile:86)
at cdt.a(SourceFile:295)
at bqi.ar(SourceFile:1325)
at bqi.q(SourceFile:1682)
at bqi.ap(SourceFile:863)
at bqi.a(SourceFile:303)
at net.minecraft.client.main.Main.main(SourceFile:120)

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

– Head –
Stacktrace:
at bbw.b(SourceFile:91)
at ami.a(SourceFile:86)
at cdt.a(SourceFile:295)
at bqi.ar(SourceFile:1325)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [chv['chowder5'/150, l='MpServer', x=99.34, y=18.51, z=-807.19]]
Chunk stats: MultiplayerChunkCache: 289, 289
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: 115.00,4.00,-819.00 - World: (115,4,-819), Chunk: (at 3,0,13 in 7,-52; contains blocks 112,0,-832 to 127,255,-817), Region: (0,-2; contains chunks 0,-64 to 31,-33, blocks 0,0,-1024 to 511,255,-513)
Level time: 72674 game time, 24094 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: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 66 total; [aez['Slime'/22, l='MpServer', x=31.06, y=5.16, z=-885.69], abn['Pig'/25, l='MpServer', x=31.19, y=4.00, z=-750.50], abn['Pig'/24, l='MpServer', x=31.78, y=4.00, z=-748.13], aez['Slime'/27, l='MpServer', x=44.84, y=4.47, z=-861.22], aez['Slime'/26, l='MpServer', x=36.09, y=5.22, z=-856.09], abf['Cow'/29, l='MpServer', x=47.59, y=4.00, z=-830.19], aez['Slime'/28, l='MpServer', x=36.44, y=4.47, z=-849.22], abn['Pig'/31, l='MpServer', x=38.19, y=4.00, z=-789.97], adt['Enderman'/30, l='MpServer', x=36.00, y=4.02, z=-800.84], abn['Pig'/32, l='MpServer', x=44.34, y=4.00, z=-781.50], abn['Pig'/33, l='MpServer', x=36.47, y=5.00, z=-737.31], abf['Cow'/38, l='MpServer', x=51.13, y=4.00, z=-834.09], abf['Cow'/39, l='MpServer', x=49.13, y=4.00, z=-840.03], acy['item.item.arrow'/42, l='MpServer', x=60.87, y=4.00, z=-820.09], acy['item.item.bone'/43, l='MpServer', x=61.13, y=4.00, z=-818.91], abf['Cow'/40, l='MpServer', x=48.88, y=4.00, z=-829.91], aff['Spider'/46, l='MpServer', x=55.97, y=4.00, z=-765.94], aff['Spider'/47, l='MpServer', x=49.25, y=4.00, z=-730.53], abn['Pig'/44, l='MpServer', x=57.13, y=4.00, z=-804.34], acy['item.item.arrow'/45, l='MpServer', x=62.38, y=4.00, z=-787.00], abn['Pig'/59, l='MpServer', x=79.66, y=4.00, z=-777.44], aff['Spider'/58, l='MpServer', x=72.28, y=4.00, z=-788.94], adr['Creeper'/57, l='MpServer', x=67.06, y=4.00, z=-801.25], abb['Bat'/61, l='MpServer', x=72.69, y=13.22, z=-752.97], aff['Spider'/60, l='MpServer', x=65.72, y=4.00, z=-767.56], aez['Slime'/70, l='MpServer', x=96.19, y=4.02, z=-865.00], chv['chowder5'/150, l='MpServer', x=99.34, y=18.51, z=-807.19], aez['Slime'/76, l='MpServer', x=102.69, y=4.00, z=-832.31], aex['Skeleton'/77, l='MpServer', x=111.16, y=4.00, z=-800.59], aez['Slime'/78, l='MpServer', x=107.50, y=4.75, z=-796.56], abf['Cow'/73, l='MpServer', x=104.22, y=4.00, z=-867.38], abf['Cow'/74, l='MpServer', x=106.63, y=4.00, z=-869.00], abf['Cow'/75, l='MpServer', x=106.75, y=4.00, z=-864.59], acy['item.item.string'/85, l='MpServer', x=118.72, y=4.00, z=-795.38], abf['Cow'/84, l='MpServer', x=118.78, y=4.00, z=-852.91], afq['Villager'/92, l='MpServer', x=138.66, y=5.00, z=-873.53], afq['Villager'/95, l='MpServer', x=142.50, y=5.00, z=-858.03], abf['Cow'/89, l='MpServer', x=128.28, y=4.00, z=-875.81], abf['Cow'/88, l='MpServer', x=133.44, y=4.00, z=-873.97], afq['Villager'/91, l='MpServer', x=137.78, y=5.00, z=-873.50], afq['Villager'/90, l='MpServer', x=142.38, y=5.00, z=-877.34], aez['Slime'/102, l='MpServer', x=129.69, y=4.09, z=-750.84], aez['Slime'/100, l='MpServer', x=141.28, y=4.02, z=-743.22], abb['Bat'/101, l='MpServer', x=131.69, y=3.88, z=-746.28], afq['Villager'/98, l='MpServer', x=144.34, y=4.02, z=-860.94], afq['Villager'/99, l='MpServer', x=143.59, y=4.00, z=-836.84], abf['Cow'/96, l='MpServer', x=130.06, y=4.00, z=-863.13], abf['Cow'/97, l='MpServer', x=137.56, y=4.00, z=-851.53], afq['Villager'/110, l='MpServer', x=148.44, y=8.00, z=-856.56], abw['Sheep'/111, l='MpServer', x=155.53, y=4.00, z=-848.50], afk['Zombie'/108, l='MpServer', x=150.13, y=5.00, z=-868.78], afk['Zombie'/109, l='MpServer', x=149.38, y=5.00, z=-868.44], afq['Villager'/106, l='MpServer', x=159.31, y=4.00, z=-871.69], afq['Villager'/107, l='MpServer', x=146.91, y=4.00, z=-874.50], aff['Spider'/116, l='MpServer', x=146.72, y=4.00, z=-775.50], aez['Slime'/115, l='MpServer', x=149.94, y=4.02, z=-814.88], afq['Villager'/114, l='MpServer', x=152.03, y=4.00, z=-839.38], afq['Villager'/113, l='MpServer', x=147.28, y=4.55, z=-864.50], afk['Zombie'/112, l='MpServer', x=145.91, y=4.00, z=-861.09], aez['Slime'/101081, l='MpServer', x=110.50, y=4.09, z=-848.22], abn['Pig'/127, l='MpServer', x=173.03, y=4.00, z=-798.06], abn['Pig'/126, l='MpServer', x=164.38, y=4.00, z=-816.88], afq['Villager'/125, l='MpServer', x=175.97, y=5.00, z=-856.31], afq['Villager'/124, l='MpServer', x=177.47, y=5.22, z=-858.81], afq['Villager'/123, l='MpServer', x=175.66, y=5.00, z=-858.38], aex['Skeleton'/122, l='MpServer', x=164.16, y=5.00, z=-872.47]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at cdu.a(SourceFile:308)
at bqi.b(SourceFile:2139)
at bqi.a(SourceFile:317)
at net.minecraft.client.main.Main.main(SourceFile:120)

– System Details –
Details:
Minecraft Version: 14w28a
Operating System: Windows 8.1 (x86) version 6.3
Java Version: 1.7.0_55, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 70463120 bytes (67 MB) / 191098880 bytes (182 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 14w28a
LWJGL: 2.9.1
OpenGL: Intel(R) HD Graphics 4000 GL version 4.0.0 - Build 10.18.10.3262, Intel
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.

Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (US)
Profiler Position: N/A (disabled)