Hopper: java.lang.NullPointerException: Saving entity NBT

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-1715091/

Crash:

java.lang.NullPointerException: Saving entity NBT
	at acz.b(SourceFile:173)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Sorry :(

Time: 7/16/14 7:43 PM
Description: Saving entity NBT

java.lang.NullPointerException: Saving entity NBT
	at acz.b(SourceFile:173)
	at wg.e(SourceFile:1107)
	at wg.d(SourceFile:1080)
	at apd.a(SourceFile:128)
	at apd.a(SourceFile:258)
	at clh.a(SourceFile:19)
	at clh.a(SourceFile:14)
	at clh.a(SourceFile:9)
	at clc.a(SourceFile:121)
	at clc.a(SourceFile:102)
	at cij.a(SourceFile:529)
	at che.a(SourceFile:1196)
	at che.a(SourceFile:1123)
	at che.b(SourceFile:972)
	at bqx.aq(SourceFile:893)
	at bqx.a(SourceFile:307)
	at net.minecraft.client.main.Main.main(SourceFile:120)


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

-- Head --
Stacktrace:
	at acz.b(SourceFile:173)

-- Entity being saved --
Details:
	Entity Type: FallingSand (acz)
	Entity ID: 784
	Entity Name: Falling Block
	Entity's Exact location: 0.00, 0.00, 0.00
	Entity's Block 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)
	Entity's Momentum: 0.00, 0.00, 0.00
	Entity's Rider: ~~ERROR~~ NullPointerException: null
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at wg.e(SourceFile:1107)
	at wg.d(SourceFile:1080)
	at apd.a(SourceFile:128)
	at apd.a(SourceFile:258)
	at clh.a(SourceFile:19)
	at clh.a(SourceFile:14)
	at clh.a(SourceFile:9)

-- Block Entity Details --
Details:
	Name: MobSpawner // bbk
	Block type: ID #52 (tile.mobSpawner // awc)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (114,61,473), Chunk: (at 2,3,9 in 7,29; contains blocks 112,0,464 to 127,255,479), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Actual block type: ID #52 (tile.mobSpawner // awc)
	Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
	at clc.a(SourceFile:121)
	at clc.a(SourceFile:102)
	at cij.a(SourceFile:529)
	at che.a(SourceFile:1196)
	at che.a(SourceFile:1123)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [cgi['squeezylemon999'/33, l='MpServer', x=53.48, y=63.61, z=455.44]]
	Chunk stats: MultiplayerChunkCache: 225, 225
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: 140.00,4.00,378.00 - World: (140,4,378), Chunk: (at 12,0,10 in 8,23; contains blocks 128,0,368 to 143,255,383), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 1099600 game time, 5013 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: 5 total; [cgi['squeezylemon999'/33, l='MpServer', x=53.48, y=63.61, z=455.44], aek['Guardian'/3, l='MpServer', x=29.75, y=61.25, z=395.25], aek['Guardian'/7, l='MpServer', x=83.41, y=61.16, z=443.41], wv['Experience Orb'/9, l='MpServer', x=51.78, y=60.00, z=365.81], ada['item.item.prismarineShard'/10, l='MpServer', x=53.88, y=60.00, z=417.44]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at cch.a(SourceFile:308)
	at bqx.b(SourceFile:2224)
	at bqx.a(SourceFile:316)
	at net.minecraft.client.main.Main.main(SourceFile:120)

-- System Details --
Details:
	Minecraft Version: 14w29b
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_09, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 114262680 bytes (108 MB) / 418607104 bytes (399 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 14w29b
	LWJGL: 2.9.1
	OpenGL: ATI Radeon HD 4500 Series GL version 2.1.8787, ATI Technologies Inc.
	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)

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-1715091/69433005/