when testing in the custom preset mountain madness I placed a ladder on the side of a stone block and it crashed and I got this

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

Time: 09/07/14 8:08 PM
Description: Unexpected error

java.lang.IllegalArgumentException: Cannot get property bck

{name=facing, clazz=class ei, values=[north, south, west, east]}

as it does not exist!
at bbw.b(SourceFile:91)
at avi.a(SourceFile:47)
at avi.a(SourceFile:35)
at apm.a(SourceFile:2320)
at ait.a(SourceFile:106)
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 avi.a(SourceFile:47)
at avi.a(SourceFile:35)
at apm.a(SourceFile:2320)
at ait.a(SourceFile:106)
at cdt.a(SourceFile:295)
at bqi.ar(SourceFile:1325)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [chv['bobbluedodo'/45, l='MpServer', x=-179.70, y=167.00, z=518.70]]
Chunk stats: MultiplayerChunkCache: 599, 599
Level seed: 0
Level generator: ID 04 - customized, ver 0. Features enabled: false
Level generator options:
Level spawn location: -22.00,64.00,265.00 - World: (-22,64,265), Chunk: (at 10,4,9 in -2,16; contains blocks -32,0,256 to -17,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Level time: 73832 game time, 73832 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: 34 total; [abz['Squid'/7814329, l='MpServer', x=-160.50, y=58.31, z=480.84], abb['Bat'/8487041, l='MpServer', x=-159.19, y=62.34, z=525.47], abb['Bat'/6835636, l='MpServer', x=-163.25, y=65.10, z=521.25], abz['Squid'/8924861, l='MpServer', x=-122.56, y=62.22, z=523.53], abz['Squid'/8924860, l='MpServer', x=-125.56, y=59.28, z=520.22], abz['Squid'/8924859, l='MpServer', x=-126.28, y=61.53, z=526.88], abz['Squid'/8924858, l='MpServer', x=-125.44, y=62.25, z=529.66], abb['Bat'/9019365, l='MpServer', x=-178.58, y=55.42, z=537.34], abb['Bat'/8624787, l='MpServer', x=-161.94, y=62.89, z=525.94], chv['bobbluedodo'/45, l='MpServer', x=-179.70, y=167.00, z=518.70], abz['Squid'/8924771, l='MpServer', x=-146.94, y=62.28, z=496.53], abz['Squid'/8924770, l='MpServer', x=-152.09, y=59.53, z=490.41], abb['Bat'/9025493, l='MpServer', x=-212.06, y=63.31, z=474.53], abz['Squid'/8924773, l='MpServer', x=-151.75, y=61.66, z=492.88], abz['Squid'/8924772, l='MpServer', x=-150.56, y=60.69, z=493.53], acy['item.item.dyePowder.black'/6579099, l='MpServer', x=-131.00, y=50.00, z=539.59], abb['Bat'/7529756, l='MpServer', x=-163.41, y=62.08, z=527.58], abz['Squid'/8924927, l='MpServer', x=-136.53, y=49.34, z=531.50], abz['Squid'/8925201, l='MpServer', x=-170.28, y=46.97, z=488.50], abb['Bat'/8627127, l='MpServer', x=-160.31, y=62.81, z=524.38], abz['Squid'/7814058, l='MpServer', x=-162.03, y=57.06, z=517.69], abb['Bat'/7369301, l='MpServer', x=-180.22, y=54.94, z=536.25], abz['Squid'/8924878, l='MpServer', x=-136.41, y=56.56, z=518.00], abz['Squid'/8924879, l='MpServer', x=-132.59, y=57.78, z=522.41], abz['Squid'/8924881, l='MpServer', x=-134.53, y=57.13, z=533.38], abz['Squid'/8924880, l='MpServer', x=-131.50, y=56.19, z=529.50], abz['Squid'/7486198, l='MpServer', x=-171.16, y=52.34, z=502.13], abz['Squid'/7814217, l='MpServer', x=-152.63, y=60.94, z=506.38], abb['Bat'/8487039, l='MpServer', x=-162.25, y=66.09, z=522.44], abz['Squid'/7814216, l='MpServer', x=-139.66, y=60.34, z=499.16], abz['Squid'/8925198, l='MpServer', x=-159.31, y=49.00, z=486.22], abb['Bat'/7107699, l='MpServer', x=-162.66, y=66.10, z=522.25], abb['Bat'/8984352, l='MpServer', x=-160.98, y=62.03, z=527.69], abz['Squid'/8925199, l='MpServer', x=-167.84, y=48.09, z=485.72]]
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 (amd64) version 6.3
Java Version: 1.7.0_60, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 331892224 bytes (316 MB) / 1018691584 bytes (971 MB) up to 2863661056 bytes (2731 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3G
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Launched Version: 14w28a
LWJGL: 2.9.1
OpenGL: GeForce GTX 560/PCIe/SSE2 GL version 4.3.0, NVIDIA Corporation
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)