Picking the block of a dragon head crashes my game.

I expected it to go ahead and work, like always.

But it crashed :L

Steps to Reproduce:
1. Go into Minecraft 15w33c
2. Place a dragon head in a new world
3. Try middle clicking it.

Heres my crash file

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 8/14/15 7:11 PM
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: 64
Entity Name: Pro_CrafterZ
Entity's Exact location: -107.44, 109.00, -182.66
Entity's Block location: -108.00,109.00,-183.00 - World: (-108,109,-183), Chunk: (at 4,6,9 in -7,-12; contains blocks -112,0,-192 to -97,255,-177), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Entity's Momentum: -0.11, -0.08, 0.02
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['Pro_CrafterZ'/64, l='MpServer', x=-107.44, y=109.00, z=-182.66]]
Chunk stats: MultiplayerChunkCache: 81, 81
Level seed: 0
Level generator: ID 04 - customized, ver 0. Features enabled: false
Level generator options:
Level spawn location: -96.00,64.00,-200.00 - World: (-96,64,-200), Chunk: (at 0,4,8 in -6,-13; contains blocks -96,0,-208 to -81,255,-193), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 4023 game time, 4023 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: 30 total; [xc['item.tile.rail'/42, l='MpServer', x=-162.13, y=26.00, z=-204.88], xc['item.tile.rail'/43, l='MpServer', x=-158.44, y=26.00, z=-203.03], xc['item.tile.rail'/47, l='MpServer', x=-169.41, y=26.00, z=-201.69], xc['item.tile.rail'/48, l='MpServer', x=-170.06, y=26.00, z=-203.53], xe['container.minecart'/54, l='MpServer', x=-144.50, y=24.06, z=-205.50], vg['Rabbit'/59, l='MpServer', x=-113.41, y=248.00, z=-185.38], vg['Rabbit'/58, l='MpServer', x=-109.59, y=241.00, z=-178.56], vg['Rabbit'/63, l='MpServer', x=-86.56, y=97.00, z=-204.38], vg['Rabbit'/62, l='MpServer', x=-99.63, y=103.00, z=-175.50], vg['Rabbit'/61, l='MpServer', x=-89.66, y=97.00, z=-182.19], vg['Rabbit'/60, l='MpServer', x=-112.66, y=245.00, z=-179.66], uw['Bat'/7596, l='MpServer', x=-150.31, y=26.09, z=-231.31], vk['Squid'/7151, l='MpServer', x=-71.47, y=46.72, z=-139.56], vk['Squid'/7152, l='MpServer', x=-79.19, y=48.44, z=-140.75], vk['Squid'/7155, l='MpServer', x=-43.50, y=50.81, z=-159.25], biz['Pro_CrafterZ'/64, l='MpServer', x=-107.44, y=109.00, z=-182.66], uw['Bat'/7548, l='MpServer', x=-156.09, y=26.38, z=-232.16], yd['Skeleton'/7514, l='MpServer', x=-149.50, y=16.00, z=-217.50], xc['item.tile.flower2.oxeyeDaisy'/6524, l='MpServer', x=-78.84, y=63.00, z=-247.75], vk['Squid'/7026, l='MpServer', x=-88.00, y=50.22, z=-134.47], xq['Creeper'/5639, l='MpServer', x=-106.47, y=95.00, z=-209.00], xc['item.tile.flower2.oxeyeDaisy'/5660, l='MpServer', x=-82.38, y=64.00, z=-247.25], xc['item.tile.flower2.oxeyeDaisy'/5662, l='MpServer', x=-78.72, y=62.00, z=-243.84], xc['item.tile.flower2.oxeyeDaisy'/5665, l='MpServer', x=-83.81, y=64.00, z=-249.56], vk['Squid'/7258, l='MpServer', x=-63.50, y=59.16, z=-190.13], vk['Squid'/7259, l='MpServer', x=-68.00, y=57.50, z=-192.56], xc['item.tile.gravel'/2355, l='MpServer', x=-165.63, y=30.00, z=-193.03], vk['Squid'/7190, l='MpServer', x=-69.09, y=46.50, z=-126.91], vk['Squid'/7171, l='MpServer', x=-166.47, y=57.56, z=-122.91], yh['Zombie'/7714, l='MpServer', x=-171.47, y=70.00, z=-259.13]]
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: Linux (i386) version 2.6.32-358.el6.i686
Java Version: 1.6.0_24, Sun Microsystems Inc.
Java VM Version: OpenJDK Client VM (mixed mode), Sun Microsystems Inc.
Memory: 210678576 bytes (200 MB) / 455917568 bytes (434 MB) up to 523501568 bytes (499 MB)
JVM Flags: 5 total; -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 15w33c
LWJGL: 2.9.4
OpenGL: Gallium 0.4 on AMD RS880 GL version 2.1 Mesa 9.0-devel, X.Org
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because ARB_framebuffer_object 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 (UK)
Profiler Position: N/A (disabled)
CPU: 1x AMD V140 Processor