Opening spectator menu crashes the client

---- Minecraft Crash Report ----
// But it works on my machine.

Time: 6-12-17 20:22
Description: Unexpected error

g: Non [a-z0-9/._-] character in path of location: minecraft:skins/CommandHelper
	at mv.<init>(SourceFile:32)
	at mv.<init>(SourceFile:37)
	at bza.e(SourceFile:108)
	at bto.<init>(SourceFile:19)
	at btv.<init>(SourceFile:43)
	at btv.<init>(SourceFile:37)
	at btp.<init>(SourceFile:15)
	at btq.<init>(SourceFile:37)
	at boz.a(SourceFile:34)
	at bmx.au(SourceFile:1324)
	at bmx.m(SourceFile:1223)
	at bmx.b(SourceFile:791)
	at bmx.a(SourceFile:380)
	at net.minecraft.client.main.Main.main(SourceFile:140)


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

-- Head --
Thread: Client thread
Stacktrace:
	at mv.<init>(SourceFile:32)
	at mv.<init>(SourceFile:37)
	at bza.e(SourceFile:108)
	at bto.<init>(SourceFile:19)
	at btv.<init>(SourceFile:43)
	at btv.<init>(SourceFile:37)
	at btp.<init>(SourceFile:15)
	at btq.<init>(SourceFile:37)
	at boz.a(SourceFile:34)
	at bmx.au(SourceFile:1324)

-- Affected level --
Details:
	Level name: MpServer
	All players: 8 total; [bzd['FVbico'/121105, l='MpServer', x=-817,77, y=26,09, z=-1231,54], bze['EDDxample'/1717, l='MpServer', x=-786,80, y=15,75, z=-1254,36], bze['Eta740'/596, l='MpServer', x=-728,97, y=11,00, z=-1255,88], bze['WARBEN'/113062, l='MpServer', x=-797,63, y=33,81, z=-1238,13], bze['theosib'/92162, l='MpServer', x=-712,33, y=1,00, z=-1232,92], bze['CommandHelper'/163970, l='MpServer', x=-780,45, y=10,52, z=-1249,71], bze['NeunEinser'/254555, l='MpServer', x=-796,05, y=14,47, z=-1255,81], bze['Gamemode3'/47489, l='MpServer', x=-721,54, y=18,76, z=-1215,74]]
	Chunk stats: MultiplayerChunkCache: 624, 624
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-756,4,-1232), Chunk: (at 12,0,0 in -48,-77; contains blocks -768,0,-1232 to -753,255,-1217), Region: (-2,-3; contains chunks -64,-96 to -33,-65, blocks -1024,0,-1536 to -513,255,-1025)
	Level time: 80713 game time, 6000 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: 52 total; [bzd['FVbico'/121105, l='MpServer', x=-817,77, y=26,09, z=-1231,54], bze['CommandHelper'/163970, l='MpServer', x=-780,45, y=10,52, z=-1249,71], bze['OreoLamp'/11005, l='MpServer', x=-746,29, y=12,22, z=-1255,68], bze['Gamemode3'/47489, l='MpServer', x=-721,54, y=18,76, z=-1215,74], bze['EDDxample'/1717, l='MpServer', x=-786,80, y=15,75, z=-1254,36], bze['theosib'/92162, l='MpServer', x=-712,33, y=1,00, z=-1232,92], bze['Eta740'/596, l='MpServer', x=-728,97, y=11,00, z=-1255,88], bze['CommandHelper'/119270, l='MpServer', x=-772,12, y=3,23, z=-1238,68], bze['NeunEinser'/766, l='MpServer', x=-738,06, y=12,28, z=-1255,17], bze['WARBEN'/113062, l='MpServer', x=-797,63, y=33,81, z=-1238,13], bze['Gamemode3'/47489, l='MpServer', x=-827,14, y=29,37, z=-1226,27], bze['theosib'/92162, l='MpServer', x=-712,33, y=1,00, z=-1232,92], bze['NeunEinser'/254555, l='MpServer', x=-815,59, y=20,09, z=-1226,00], bze['WARBEN'/113062, l='MpServer', x=-797,63, y=33,81, z=-1238,13], bze['CommandHelper'/163970, l='MpServer', x=-780,45, y=10,52, z=-1249,71], bze['NeunEinser'/254555, l='MpServer', x=-796,05, y=14,47, z=-1255,81], agg['Birch Log'/315700, l='MpServer', x=-825,81, y=1,00, z=-1223,27], agg['Sticky Piston'/315701, l='MpServer', x=-826,59, y=1,00, z=-1223,95], agg['Block of Iron'/315702, l='MpServer', x=-829,47, y=1,00, z=-1227,32], agg['Bone Meal'/315703, l='MpServer', x=-821,39, y=1,00, z=-1228,26], bze['EDDxample'/1717, l='MpServer', x=-786,80, y=15,75, z=-1254,36], bze['Gamemode3'/47489, l='MpServer', x=-827,04, y=29,37, z=-1226,30], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Block of Redstone'/315699, l='MpServer', x=-823,18, y=1,00, z=-1223,70], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Redstone Dust'/315708, l='MpServer', x=-827,07, y=1,00, z=-1226,16], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Anvil'/315709, l='MpServer', x=-831,52, y=1,00, z=-1222,00], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Grass'/315710, l='MpServer', x=-831,02, y=1,00, z=-1223,47], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['White Stained Glass'/315704, l='MpServer', x=-827,68, y=1,00, z=-1227,93], bze['CommandHelper'/163970, l='MpServer', x=-731,92, y=10,99, z=-1269,29], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Weighted Pressure Plate (Light)'/315705, l='MpServer', x=-827,24, y=1,00, z=-1229,48], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Powered Rail'/315706, l='MpServer', x=-830,07, y=1,00, z=-1222,41], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], agg['Observer'/315707, l='MpServer', x=-825,12, y=1,00, z=-1226,76], bze['Gamemode3'/47489, l='MpServer', x=-827,03, y=29,37, z=-1226,30], ahg['Slime'/316612, l='MpServer', x=-741,01, y=1,00, z=-1194,48], bze['OreoLamp'/314660, l='MpServer', x=-735,58, y=12,22, z=-1253,98], bze['OreoLamp'/314660, l='MpServer', x=-737,90, y=8,10, z=-1238,23], bze['Gamemode3'/47489, l='MpServer', x=-827,05, y=1,00, z=-1226,38], ajf['entity.MinecartRideable.name'/99142, l='MpServer', x=-762,12, y=7,18, z=-1204,50], bze['Gamemode3'/47489, l='MpServer', x=-721,54, y=18,76, z=-1215,74], bze['Eta740'/596, l='MpServer', x=-728,97, y=11,00, z=-1255,88], agg['Lever'/312016, l='MpServer', x=-815,37, y=15,00, z=-1232,01], bze['NeunEinser'/254555, l='MpServer', x=-796,05, y=14,47, z=-1255,81], bze['NeunEinser'/245703, l='MpServer', x=-738,12, y=12,28, z=-1255,10], ajf['entity.MinecartRideable.name'/301937, l='MpServer', x=-798,50, y=13,06, z=-1259,50]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bxe.a(SourceFile:356)
	at bmx.b(SourceFile:1838)
	at bmx.a(SourceFile:394)
	at net.minecraft.client.main.Main.main(SourceFile:140)

-- System Details --
Details:
	Minecraft Version: 17w49a
	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: 442941992 bytes (422 MB) / 1038876672 bytes (990 MB) up to 2112618496 bytes (2014 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xms1024M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 17w49a
	LWJGL: 3.1.2 build 29
	OpenGL: GeForce GTX 660/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: 
	Current Language: ~~ERROR~~ NullPointerException: null
	Profiler Position: N/A (disabled)
	CPU: 4x Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz