17w48a crash report upon loading structure

---- Minecraft Crash Report ----
// Ooh. Shiny.

Time: 5/12/17 10:11 PM
Description: Rendering Block Entity

java.lang.IllegalArgumentException: Cannot get property bbc{name=facing, clazz=class dz, values=[north, east, south, west]} as it does not exist in baq{block=minecraft:air, properties=[]}
	at baq$a.c(SourceFile:174)
	at cbu.a(SourceFile:37)
	at cbu.a(SourceFile:18)
	at cbn.a(SourceFile:134)
	at cbn.a(SourceFile:122)
	at bzo.a(SourceFile:673)
	at bzi.b(SourceFile:1185)
	at bzi.a(SourceFile:1093)
	at bzi.a(SourceFile:951)
	at bmm.b(SourceFile:820)
	at bmm.a(SourceFile:381)
	at net.minecraft.client.main.Main.main(SourceFile:134)


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

-- Head --
Thread: Client thread
Stacktrace:
	at baq$a.c(SourceFile:174)
	at cbu.a(SourceFile:37)
	at cbu.a(SourceFile:18)

-- Block Entity Details --
Details:
	Name: minecraft:sign // azo
	Block: minecraft:air
	Block location: World: (34,11,19), Chunk: (at 2,0,3 in 2,1; contains blocks 32,0,16 to 47,255,31), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Block: minecraft:air
	Block location: World: (34,11,19), Chunk: (at 2,0,3 in 2,1; contains blocks 32,0,16 to 47,255,31), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Stacktrace:
	at cbn.a(SourceFile:134)
	at cbn.a(SourceFile:122)
	at bzo.a(SourceFile:673)
	at bzi.b(SourceFile:1185)
	at bzi.a(SourceFile:1093)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [byv['CreepaShadowz'/0, l='MpServer', x=24.22, y=4.00, z=-9.54]]
	Chunk stats: MultiplayerChunkCache: 599, 599
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options:
	Level spawn location: World: (8,4,8), Chunk: (at 8,0,8 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: 19446 game time, 19446 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: 1 total; [byv['CreepaShadowz'/0, l='MpServer', x=24.22, y=4.00, z=-9.54]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bww.a(SourceFile:357)
	at bmm.b(SourceFile:1838)
	at bmm.a(SourceFile:390)
	at net.minecraft.client.main.Main.main(SourceFile:134)

-- System Details --
Details:
	Minecraft Version: 17w48a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 373663384 bytes (356 MB) / 1090519040 bytes (1040 MB) up to 3221225472 bytes (3072 MB)
	JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3G -Xmn1G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 17w48a
	LWJGL: 3.1.2 build 29
	OpenGL: GeForce GTX 960/PCIe/SSE2 GL version 4.6.0 NVIDIA 388.13, 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.
VBOs are available because OpenGL 1.5 is supported.

	Using VBOs: Yes
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: vanilla
	Current Language: ~~ERROR~~ NullPointerException: null
	Profiler Position: N/A (disabled)
	CPU: 8x Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz