CTRL + Middle Mouse Button on an head crashes the game

Incomplete without a crash report from ([minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/finding-minecraft-data-folder]). Please attach it so that we can diagnose your issue.

Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 14/08/15 20.01
Description: Ticking entity

java.lang.NullPointerException: Ticking entity
at acj.a(SourceFile:401)
at yp.k(SourceFile:282)
at yq.m(SourceFile:404)
at biz.m(SourceFile:708)
at rd.r_(SourceFile:1436)
at yq.r_(SourceFile:229)
at biz.r_(SourceFile:114)
at agh.a(SourceFile:1414)
at agh.g(SourceFile:1392)
at agh.j(SourceFile:1285)
at ayy.s(SourceFile:1845)
at ayy.au(SourceFile:879)
at ayy.a(SourceFile:328)
at net.minecraft.client.main.Main.main(SourceFile:125)

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

– Head –
Stacktrace:
at acj.a(SourceFile:401)
at yp.k(SourceFile:282)
at yq.m(SourceFile:404)
at biz.m(SourceFile:708)
at rd.r_(SourceFile:1436)
at yq.r_(SourceFile:229)
at biz.r_(SourceFile:114)
at agh.a(SourceFile:1414)
at agh.g(SourceFile:1392)

– Entity being ticked –
Details:
Entity Type: null (biz)
Entity ID: 255
Entity Name: federicorl
Entity's Exact location: 180,21, 15,00, 640,61
Entity's Block location: 180,00,15,00,640,00 - World: (180,15,640), Chunk: (at 4,0,0 in 11,40; contains blocks 176,0,640 to 191,255,655), Region: (0,1; contains chunks 0,32 to 31,63, blocks 0,0,512 to 511,255,1023)
Entity's Momentum: 0,00, -0,08, 0,00
Entity's Rider: ~_ERROR~ NullPointerException: null
Entity's Vehicle: ~_ERROR~ NullPointerException: null
Stacktrace:
at agh.j(SourceFile:1285)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [biz['federicorl'/255, l='MpServer', x=180,21, y=15,00, z=640,61]]
Chunk stats: MultiplayerChunkCache: 360, 360
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: 40,00,64,00,207,00 - World: (40,64,207), Chunk: (at 8,4,15 in 2,12; contains blocks 32,0,192 to 47,255,207), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 455131 game time, 167820 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: spectator (ID 3). Hardcore: false. Cheats: false
Forced entities: 92 total; [ws['Painting'/96, l='MpServer', x=36,50, y=65,50, z=237,97], ws['Painting'/95, l='MpServer', x=44,50, y=65,50, z=202,03], uz['Chicken'/7206, l='MpServer', x=163,47, y=72,00, z=575,63], uz['Chicken'/7211, l='MpServer', x=236,31, y=72,00, z=641,63], uz['Chicken'/7212, l='MpServer', x=237,47, y=72,00, z=642,41], xc['item.item.egg'/7213, l='MpServer', x=237,47, y=72,00, z=643,31], va['Cow'/7214, l='MpServer', x=125,00, y=78,00, z=572,44], va['Cow'/7217, l='MpServer', x=110,44, y=84,00, z=585,69], va['Cow'/7218, l='MpServer', x=146,69, y=85,00, z=596,53], vf['Pig'/7220, l='MpServer', x=173,22, y=71,00, z=594,88], va['Cow'/7221, l='MpServer', x=160,03, y=97,00, z=603,16], va['Cow'/7222, l='MpServer', x=125,84, y=81,00, z=581,06], va['Cow'/7226, l='MpServer', x=145,56, y=91,00, z=578,50], va['Cow'/7227, l='MpServer', x=226,50, y=79,00, z=671,50], va['Cow'/7228, l='MpServer', x=229,50, y=73,00, z=671,50], va['Cow'/7229, l='MpServer', x=224,78, y=88,00, z=671,59], uz['Chicken'/7231, l='MpServer', x=164,50, y=72,00, z=586,38], uz['Chicken'/7232, l='MpServer', x=165,56, y=74,00, z=589,53], vf['Pig'/7233, l='MpServer', x=165,28, y=72,00, z=581,47], xc['item.item.egg'/7235, l='MpServer', x=162,13, y=76,00, z=587,88], xc['item.item.egg'/7236, l='MpServer', x=164,13, y=72,00, z=586,91], vh['Sheep'/7237, l='MpServer', x=106,50, y=70,00, z=704,50], va['Cow'/7238, l='MpServer', x=220,50, y=97,00, z=670,50], va['Cow'/7239, l='MpServer', x=208,81, y=120,00, z=658,16], va['Cow'/7240, l='MpServer', x=139,25, y=81,00, z=580,31], va['Cow'/7241, l='MpServer', x=129,13, y=80,00, z=603,63], va['Cow'/7242, l='MpServer', x=133,84, y=89,00, z=605,00], uz['Chicken'/7251, l='MpServer', x=243,50, y=72,00, z=637,50], uz['Chicken'/7252, l='MpServer', x=258,59, y=72,00, z=628,66], uz['Chicken'/7258, l='MpServer', x=239,88, y=72,00, z=627,94], uz['Chicken'/7275, l='MpServer', x=259,38, y=69,00, z=561,47], uz['Chicken'/7287, l='MpServer', x=225,56, y=73,00, z=611,50], vf['Pig'/7288, l='MpServer', x=224,84, y=73,00, z=610,00], xc['item.item.egg'/7289, l='MpServer', x=224,75, y=73,00, z=611,84], vf['Pig'/7298, l='MpServer', x=205,81, y=72,00, z=592,84], vf['Pig'/7299, l='MpServer', x=185,97, y=70,00, z=600,00], vf['Pig'/7301, l='MpServer', x=198,91, y=74,00, z=578,22], uz['Chicken'/7304, l='MpServer', x=183,19, y=70,00, z=588,94], uz['Chicken'/7305, l='MpServer', x=188,41, y=70,00, z=585,28], uz['Chicken'/7306, l='MpServer', x=176,66, y=69,00, z=585,63], uz['Chicken'/7307, l='MpServer', x=178,66, y=69,00, z=587,34], xc['item.item.egg'/7308, l='MpServer', x=178,13, y=69,00, z=586,53], xc['item.item.egg'/7309, l='MpServer', x=176,84, y=69,00, z=585,88], vf['Pig'/7316, l='MpServer', x=184,44, y=72,00, z=573,28], va['Cow'/7324, l='MpServer', x=137,56, y=76,00, z=656,78], vf['Pig'/7325, l='MpServer', x=198,00, y=72,00, z=610,03], va['Cow'/7327, l='MpServer', x=134,28, y=76,00, z=649,25], va['Cow'/7328, l='MpServer', x=137,88, y=75,00, z=652,44], va['Cow'/7329, l='MpServer', x=138,44, y=75,25, z=654,13], va['Cow'/7335, l='MpServer', x=158,81, y=79,00, z=660,84], va['Cow'/7341, l='MpServer', x=153,41, y=78,00, z=641,72], vf['Pig'/7342, l='MpServer', x=236,56, y=72,00, z=569,78], va['Cow'/7344, l='MpServer', x=127,91, y=77,00, z=653,91], uz['Chicken'/7354, l='MpServer', x=231,59, y=74,00, z=602,38], vf['Pig'/7355, l='MpServer', x=235,16, y=74,00, z=593,69], uz['Chicken'/7356, l='MpServer', x=233,50, y=75,00, z=592,72], xc['item.item.egg'/7357, l='MpServer', x=237,69, y=74,00, z=597,13], vf['Pig'/7362, l='MpServer', x=241,75, y=72,00, z=607,91], va['Cow'/7367, l='MpServer', x=155,97, y=78,00, z=658,69], va['Cow'/7368, l='MpServer', x=144,41, y=76,00, z=663,22], uz['Chicken'/7369, l='MpServer', x=235,03, y=72,00, z=577,41], uz['Chicken'/7370, l='MpServer', x=235,84, y=72,00, z=577,66], xc['item.item.egg'/7371, l='MpServer', x=233,94, y=75,00, z=591,97], xc['item.item.egg'/7372, l='MpServer', x=235,06, y=72,00, z=577,25], va['Cow'/7388, l='MpServer', x=131,88, y=80,00, z=622,94], vh['Sheep'/7389, l='MpServer', x=115,19, y=71,00, z=708,47], uz['Chicken'/7390, l='MpServer', x=192,22, y=110,00, z=665,25], uz['Chicken'/7391, l='MpServer', x=197,50, y=109,00, z=658,50], xc['item.item.egg'/7392, l='MpServer', x=198,31, y=109,00, z=658,00], va['Cow'/7393, l='MpServer', x=201,59, y=111,00, z=660,53], uz['Chicken'/7394, l='MpServer', x=201,59, y=112,00, z=666,53], va['Cow'/7395, l='MpServer', x=207,53, y=119,00, z=663,03], uz['Chicken'/7396, l='MpServer', x=203,47, y=115,00, z=669,63], xc['item.item.egg'/7397, l='MpServer', x=200,97, y=112,00, z=666,38], xc['item.item.egg'/7398, l='MpServer', x=203,72, y=115,00, z=669,38], vh['Sheep'/7399, l='MpServer', x=106,91, y=71,00, z=702,19], xc['item.item.egg'/7400, l='MpServer', x=191,66, y=110,00, z=665,41], va['Cow'/7406, l='MpServer', x=210,78, y=108,00, z=647,41], va['Cow'/7410, l='MpServer', x=136,38, y=83,00, z=627,63], va['Cow'/7420, l='MpServer', x=150,09, y=83,00, z=628,88], va['Cow'/7422, l='MpServer', x=121,00, y=79,00, z=628,06], va['Cow'/7429, l='MpServer', x=120,91, y=79,00, z=626,91], va['Cow'/7436, l='MpServer', x=126,69, y=79,00, z=609,78], va['Cow'/7437, l='MpServer', x=119,94, y=79,00, z=623,84], va['Cow'/7438, l='MpServer', x=104,22, y=80,00, z=618,34], va['Cow'/7439, l='MpServer', x=115,31, y=80,00, z=610,19], va['Cow'/7444, l='MpServer', x=164,34, y=93,00, z=621,59], va['Cow'/7445, l='MpServer', x=168,34, y=97,00, z=618,56], biz['federicorl'/255, l='MpServer', x=180,50, y=15,00, z=640,50], xc['item.item.egg'/7564, l='MpServer', x=242,91, y=72,00, z=637,28], xc['item.item.egg'/7592, l='MpServer', x=182,97, y=70,00, z=588,91], biz['federicorl'/255, l='MpServer', x=180,21, y=15,00, z=640,61]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bhb.a(SourceFile:314)
at ayy.b(SourceFile:2297)
at ayy.a(SourceFile:337)
at net.minecraft.client.main.Main.main(SourceFile:125)

– System Details –
Details:
Minecraft Version: 15w33c
Operating System: Windows 8.1 (x86) version 6.3
Java Version: 1.8.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 121756816 bytes (116 MB) / 437100544 bytes (416 MB) up to 523501568 bytes (499 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Launched Version: 15w33c
LWJGL: 2.9.4
OpenGL: GeForce GTS 250/PCIe/SSE2 GL version 3.3.0, 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.
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 AMD Athlon(tm) II X4 620 Processor