Game crashes when sand block placed

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

Time: 12/2/15 5:41 PM
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
at rx.a_(SourceFile:409)
at zo.a(SourceFile:1818)
at rx.a(SourceFile:1198)
at bbz.au(SourceFile:1435)
at bbz.ax(SourceFile:1934)
at bbz.aw(SourceFile:1752)
at bbz.s(SourceFile:1596)
at bbz.as(SourceFile:942)
at bbz.a(SourceFile:386)
at net.minecraft.client.main.Main.main(SourceFile:122)

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

– Head –
Stacktrace:
at rx.a_(SourceFile:409)
at zo.a(SourceFile:1818)
at rx.a(SourceFile:1198)
at bbz.au(SourceFile:1435)
at bbz.ax(SourceFile:1934)
at bbz.aw(SourceFile:1752)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bmg['Captain_Dirk50'/96, l='MpServer', x=4.30, y=64.25, z=-135.30]]
Chunk stats: MultiplayerChunkCache: 271, 271
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (-16,64,-64), Chunk: (at 0,4,0 in -1,-4; contains blocks -16,0,-64 to -1,255,-49), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 3600 game time, 3600 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: 46 total; [zb['Skeleton'/2048, l='MpServer', x=7.50, y=14.00, z=-119.50], yz['Shulker'/2059, l='MpServer', x=-5.50, y=78.00, z=-87.50], zb['Skeleton'/2126, l='MpServer', x=61.50, y=13.00, z=-163.50], yn['Creeper'/2151, l='MpServer', x=8.50, y=14.00, z=-106.50], zf['Zombie'/2167, l='MpServer', x=-20.50, y=37.00, z=-61.50], vq['Bat'/2175, l='MpServer', x=-39.25, y=22.10, z=-156.25], vu['Cow'/1788, l='MpServer', x=-14.31, y=72.00, z=-100.56], vu['Cow'/1789, l='MpServer', x=-11.78, y=77.00, z=-89.69], vq['Bat'/2316, l='MpServer', x=-17.22, y=38.10, z=-69.44], vq['Bat'/2317, l='MpServer', x=-7.50, y=36.00, z=-72.56], vq['Bat'/2319, l='MpServer', x=-12.79, y=37.74, z=-72.44], zf['Zombie'/791, l='MpServer', x=5.06, y=49.00, z=-106.53], zf['Zombie'/2342, l='MpServer', x=46.50, y=18.00, z=-173.50], zf['Zombie'/2343, l='MpServer', x=38.53, y=22.00, z=-171.06], yz['Shulker'/2351, l='MpServer', x=-8.50, y=70.00, z=-114.50], ze['Witch'/2364, l='MpServer', x=-18.50, y=23.00, z=-93.50], zf['Zombie'/2372, l='MpServer', x=9.50, y=15.00, z=-89.50], zb['Skeleton'/2395, l='MpServer', x=-18.50, y=13.00, z=-189.50], zb['Skeleton'/2396, l='MpServer', x=-22.50, y=13.00, z=-189.50], zf['Zombie'/2399, l='MpServer', x=0.50, y=23.00, z=-208.50], zb['Skeleton'/2401, l='MpServer', x=4.50, y=23.00, z=-210.50], zb['Skeleton'/2402, l='MpServer', x=5.50, y=23.00, z=-211.50], zf['Zombie'/2403, l='MpServer', x=-9.13, y=23.00, z=-204.66], zf['Zombie'/1893, l='MpServer', x=-22.50, y=11.00, z=-176.50], zd['Spider'/871, l='MpServer', x=-7.31, y=49.09, z=-114.31], vq['Bat'/370, l='MpServer', x=-20.25, y=20.10, z=-103.75], zb['Skeleton'/2424, l='MpServer', x=-1.50, y=35.00, z=-68.50], wa['Sheep'/2440, l='MpServer', x=-17.50, y=72.00, z=-88.50], zb['Skeleton'/2454, l='MpServer', x=-12.50, y=18.00, z=-106.50], yn['Creeper'/2457, l='MpServer', x=-43.50, y=23.00, z=-151.50], yn['Creeper'/2458, l='MpServer', x=-42.66, y=23.00, z=-151.91], yn['Creeper'/2459, l='MpServer', x=-41.50, y=23.00, z=-153.50], yn['Creeper'/2460, l='MpServer', x=-43.50, y=23.00, z=-153.84], zd['Spider'/2461, l='MpServer', x=10.50, y=23.00, z=-211.50], zd['Spider'/2462, l='MpServer', x=8.50, y=23.00, z=-211.50], zd['Spider'/2465, l='MpServer', x=13.50, y=23.00, z=-211.50], vq['Bat'/2484, l='MpServer', x=-43.31, y=19.25, z=-143.63], bmg['Captain_Dirk50'/96, l='MpServer', x=4.30, y=64.25, z=-135.30], zf['Zombie'/2521, l='MpServer', x=-0.27, y=48.00, z=-109.09], zf['Zombie'/2522, l='MpServer', x=-0.50, y=47.00, z=-111.50], zf['Zombie'/2523, l='MpServer', x=-1.47, y=47.00, z=-109.66], zf['Zombie'/2524, l='MpServer', x=-0.86, y=47.00, z=-109.31], vq['Bat'/2532, l='MpServer', x=25.72, y=17.00, z=-133.15], vq['Bat'/2533, l='MpServer', x=-14.60, y=30.01, z=-87.35], zf['Zombie'/2036, l='MpServer', x=1.50, y=28.00, z=-112.50], zb['Skeleton'/2047, l='MpServer', x=8.50, y=14.00, z=-117.50]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bkh.a(SourceFile:364)
at bbz.b(SourceFile:2496)
at bbz.a(SourceFile:400)
at net.minecraft.client.main.Main.main(SourceFile:122)

– System Details –
Details:
Minecraft Version: 15w49a
Operating System: Windows 8.1 (amd64) version 6.3
Java Version: 1.8.0_45, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 188307320 bytes (179 MB) / 432394240 bytes (412 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: 12, tallocated: 94
Launched Version: 15w49a
LWJGL: 2.9.4
OpenGL: GeForce GT 555M/PCIe/SSE2 GL version 4.5.0 NVIDIA 353.62, 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: English (US)
Profiler Position: N/A (disabled)
CPU: 4x Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz