[EXPLOITABLE]: Painting+mob spawner

Okay, so crash log:

---- Minecraft Crash Report ----
// My bad.

Time: 11/03/15 14:30
Description: Rendering entity in world

java.lang.NullPointerException: Rendering entity in world
	at bjs.a(SourceFile:35)
	at bjs.a(SourceFile:16)
	at biv.a(SourceFile:295)
	at biv.a(SourceFile:282)
	at bhi.a(SourceFile:28)
	at bhi.a(SourceFile:14)
	at bhi.a(SourceFile:9)
	at bhd.a(SourceFile:114)
	at bhd.a(SourceFile:102)
	at bfs.a(SourceFile:615)
	at bfl.a(SourceFile:1244)
	at bfl.b(SourceFile:1149)
	at bfl.a(SourceFile:1002)
	at avf.av(SourceFile:914)
	at avf.a(SourceFile:325)
	at net.minecraft.client.main.Main.main(SourceFile:124)


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

-- Head --
Stacktrace:
	at bjs.a(SourceFile:35)
	at bjs.a(SourceFile:16)

-- Entity being rendered --
Details:
	Entity Type: Painting (ur)
	Entity ID: 14
	Entity Name: Painting
	Entity's Exact location: -4.00, 0.00, 0.00
	Entity's Block location: -4.00,0.00,0.00 - World: (-4,0,0), Chunk: (at 12,0,0 in -1,0; contains blocks -16,0,0 to -1,255,15), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Entity's Momentum: 0.00, 0.00, 0.00
	Entity's Rider: ~~ERROR~~ NullPointerException: null
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null

-- Renderer details --
Details:
	Assigned renderer: bjs@4c12f54a
	Location: 0.00,0.00,0.00 - World: (0,0,0), Chunk: (at 0,0,0 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)
	Rotation: 0.0
	Delta: 0.8871708
Stacktrace:
	at biv.a(SourceFile:295)
	at biv.a(SourceFile:282)
	at bhi.a(SourceFile:28)
	at bhi.a(SourceFile:14)
	at bhi.a(SourceFile:9)

-- Block Entity Details --
Details:
	Name: MobSpawner // alm
	Block type: ID #52 (tile.mobSpawner // ahz)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (-54,65,4534), Chunk: (at 10,4,6 in -4,283; contains blocks -64,0,4528 to -49,255,4543), Region: (-1,8; contains chunks -32,256 to -1,287, blocks -512,0,4096 to -1,255,4607)
	Actual block type: ID #52 (tile.mobSpawner // ahz)
	Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
	at bhd.a(SourceFile:114)
	at bhd.a(SourceFile:102)
	at bfs.a(SourceFile:615)
	at bfl.a(SourceFile:1244)
	at bfl.b(SourceFile:1149)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bex['AWelshGamer_'/1417146, l='MpServer', x=-50.39, y=65.00, z=4533.89]]
	Chunk stats: MultiplayerChunkCache: 441, 441
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: -265.00,65.00,223.00 - World: (-265,65,223), Chunk: (at 7,4,15 in -17,13; contains blocks -272,0,208 to -257,255,223), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
	Level time: 1048992398 game time, 17647566000 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: 12 total; [bex['AWelshGamer_'/1417146, l='MpServer', x=-50.39, y=65.00, z=4533.89], va['item.item.monsterPlacer'/1417149, l='MpServer', x=-56.34, y=65.00, z=4533.03], va['item.item.monsterPlacer'/1417148, l='MpServer', x=-56.34, y=65.00, z=4531.63], va['item.item.monsterPlacer'/1417150, l='MpServer', x=-56.16, y=65.00, z=4532.75], va['item.item.monsterPlacer'/1417147, l='MpServer', x=-56.66, y=65.00, z=4533.03], vh['entity.MinecartRideable.name'/1417157, l='MpServer', x=-17.06, y=76.00, z=4543.53], va['item.item.monsterPlacer'/1417156, l='MpServer', x=-56.53, y=65.00, z=4534.63], vh['entity.MinecartRideable.name'/1417158, l='MpServer', x=-10.50, y=76.00, z=4543.50], va['item.item.monsterPlacer'/1417153, l='MpServer', x=-57.25, y=65.00, z=4533.47], va['item.item.monsterPlacer'/1417152, l='MpServer', x=-56.97, y=65.00, z=4532.63], va['item.item.monsterPlacer'/1417155, l='MpServer', x=-56.19, y=65.00, z=4533.28], va['item.item.monsterPlacer'/1417154, l='MpServer', x=-55.31, y=65.00, z=4532.75]]
	Retry entities: 0 total; []
	Server brand: Spigot
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bdc.a(SourceFile:309)
	at avf.b(SourceFile:2296)
	at avf.a(SourceFile:334)
	at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
	Minecraft Version: 1.8.3
	Operating System: Windows 7 (amd64) version 6.1
	CPU: 4x AMD A6-3420M APU with Radeon(tm) HD Graphics
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 63937904 bytes (60 MB) / 248123392 bytes (236 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: 13, tallocated: 95
	Launched Version: 1.8.3
	LWJGL: 2.9.4
	OpenGL: AMD Radeon(TM) HD 6520G GL version 4.1.11159 Compatibility Profile Context, 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: 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)