Some person has a head entity that will crash the game for all except the person who made it in creative.
Someone either destroy their plot and do something, or delete the player.dat please. :L
(NOTE: Highlighted in bold is the juicy part)

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 12/09/16 16:41
Description: Rendering Block Entity

com.google.common.util.concurrent.UncheckedExecutionException: java.lang.NullPointerException
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2201)
at com.google.common.cache.LocalCache.get(LocalCache.java:3934)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3938)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4821)
at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4827)
at bxk.a(SourceFile:126)
at bqn.a(SourceFile:81)
at bqn.a(SourceFile:43)
at bqn.a(SourceFile:22)
at bqf.a(SourceFile:129)
at bqf.a(SourceFile:117)
at boh.a(SourceFile:662)
at bnz.a(SourceFile:1266)
at bnz.b(SourceFile:1163)
at bnz.a(SourceFile:1018)
at bcx.av(SourceFile:991)
at bcx.a(SourceFile:396)
at net.minecraft.client.main.Main.main(SourceFile:124)
Caused by: java.lang.NullPointerException
at com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService.isWhitelistedDomain(YggdrasilMinecraftSessionService.java:210)
at com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService.getTextures(YggdrasilMinecraftSessionService.java:149)
at bxk$1.a(SourceFile:47)
at bxk$1.load(SourceFile:44)
at com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3524)
at com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2317)
at com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2280)
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2195)
... 17 more

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

-- Head --
Thread: Client thread
Stacktrace:
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2201)
at com.google.common.cache.LocalCache.get(LocalCache.java:3934)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3938)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4821)
at com.google.common.cache.LocalCache$LocalLoadingCache.getUnchecked(LocalCache.java:4827)
at bxk.a(SourceFile:126)
at bqn.a(SourceFile:81)
at bqn.a(SourceFile:43)
at bqn.a(SourceFile:22)

-- Block Entity Details --
Details:
Name: Skull // ard
Block type: ID #144 (tile.skull // aoy)
Block data value: 1 / 0x1 / 0b0001
Block location: World: (-115,16,-1584), Chunk: (at 13,1,0 in -8,-99; contains blocks -128,0,-1584 to -113,255,-1569), Region: (-1,-4; contains chunks -32,-128 to -1,-97, blocks -512,0,-2048 to -1,255,-1537)
Actual block type: ID #144 (tile.skull // aoy)
Actual block data value: 1 / 0x1 / 0b0001
Stacktrace:
at bqf.a(SourceFile:129)
at bqf.a(SourceFile:117)
at boh.a(SourceFile:662)
at bnz.a(SourceFile:1266)
at bnz.b(SourceFile:1163)

-- Affected level --
Details:
Level name: MpServer
All players: 1 total; [bnn['Cg4PlaysMC'/1493, l='MpServer', x=-125.78, y=29.30, z=-1568.70]]
Chunk stats: MultiplayerChunkCache: 441, 441
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (0,16,0), Chunk: (at 0,1,0 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: 282765485 game time, 283081468 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; [bnn['Cg4PlaysMC'/1493, l='MpServer', x=-125.78, y=29.30, z=-1568.70]]
Retry entities: 0 total; []
Server brand: Spigot
Server type: Non-integrated multiplayer server
Stacktrace:
at bln.a(SourceFile:364)
at bcx.b(SourceFile:2535)
at bcx.a(SourceFile:405)
at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
Minecraft Version: 1.10.2
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: 66680784 bytes (63 MB) / 284205056 bytes (271 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.10.2
LWJGL: 2.9.4
OpenGL: AMD Radeon (TM) R7 370 Series GL version 4.5.13399 Compatibility Profile Context 15.201.1151.1008, ATI Technologies Inc.
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: No
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)
CPU: 8x Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz