Crash - java.lang.NullPointerException after entering a world

I entered a world that was designed for 1.6.4 and this crash happened.

I think this is the first report of this crash because I copied the code and pasted it here and it said this:

The crash report you provided was not found anywhere. That means that nobody has reported this to us, and we probably don't even know it exists! Feel like helping us out? Please report it to us over at the bug tracker.

Here is the crash report.

---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 21-09-2013 19:10
Description: Rendering entity in world

java.lang.NullPointerException
	at biw.a(SourceFile:74)
	at bjt.a(SourceFile:53)
	at bjt.a(SourceFile:16)
	at bjq.a(SourceFile:215)
	at bjq.a(SourceFile:196)
	at bmt.a(SourceFile:30)
	at bmt.a(SourceFile:15)
	at bmt.a(SourceFile:10)
	at bmy.a(SourceFile:100)
	at bmy.a(SourceFile:92)
	at bip.a(SourceFile:354)
	at bii.a(SourceFile:974)
	at bii.b(SourceFile:807)
	at awp.aa(SourceFile:754)
	at awp.e(SourceFile:677)
	at net.minecraft.client.main.Main.main(SourceFile:104)


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

-- Head --
Stacktrace:
	at biw.a(SourceFile:74)
	at bjt.a(SourceFile:53)
	at bjt.a(SourceFile:16)

-- Entity being rendered --
Details:
	Entity Type: FallingSand (ts)
	Entity ID: 224
	Entity Name: Falling Block
	Entity's Exact location: 26,57, -2,62, -6,89
	Entity's Block location: World: (26,-3,-7), Chunk: (at 10,-1,9 in 1,-1; contains blocks 16,0,-16 to 31,255,-1), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
	Entity's Momentum: 0,00, 0,00, 0,00
	Immitating block ID: -1
	Immitating block data: 0

-- Renderer details --
Details:
	Assigned renderer: bjt@82448a
	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: 0.48164332
Stacktrace:
	at bjq.a(SourceFile:215)
	at bjq.a(SourceFile:196)
	at bmt.a(SourceFile:30)
	at bmt.a(SourceFile:15)
	at bmt.a(SourceFile:10)

-- Tile Entity Details --
Details:
	Name: MobSpawner // avd
	Block type: ID #52 (tile.mobSpawner // asa)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (521,67,248), Chunk: (at 9,4,8 in 32,15; contains blocks 512,0,240 to 527,255,255), Region: (1,0; contains chunks 32,0 to 63,31, blocks 512,0,0 to 1023,255,511)
	Actual block type: ID #52 (tile.mobSpawner // asa)
	Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
	at bmy.a(SourceFile:100)
	at bmy.a(SourceFile:92)
	at bip.a(SourceFile:354)
	at bii.a(SourceFile:974)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bgh['Daniel_Mestre'/74, l='MpServer', x=494,43, y=69,62, z=254,89]]
	Chunk stats: MultiplayerChunkCache: 225, 225
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (497,69,254), Chunk: (at 1,4,14 in 31,15; contains blocks 496,0,240 to 511,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 3042034 game time, 54000 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: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 50 total; [us['Stalfos Guard'/3, l='MpServer', x=509,50, y=78,00, z=245,44], us['Stalfos Guard'/4, l='MpServer', x=509,50, y=78,00, z=264,50], pk['Painting'/41, l='MpServer', x=543,06, y=95,50, z=250,50], ts['Falling Block'/175, l='MpServer', x=519,50, y=71,82, z=250,53], ts['Falling Block'/174, l='MpServer', x=521,50, y=71,82, z=259,47], tv['entity.MinecartChest.name'/36, l='MpServer', x=522,50, y=32,50, z=274,50], tv['entity.MinecartChest.name'/37, l='MpServer', x=527,50, y=37,50, z=328,50], us['Stalfos Guard'/42, l='MpServer', x=536,50, y=94,00, z=255,50], tv['entity.MinecartChest.name'/40, l='MpServer', x=543,50, y=34,50, z=205,50], pk['Painting'/41, l='MpServer', x=543,06, y=95,50, z=250,50], ts['Falling Block'/167, l='MpServer', x=519,50, y=71,43, z=250,16], ts['Falling Block'/166, l='MpServer', x=521,50, y=71,43, z=259,84], ts['Falling Block'/186, l='MpServer', x=521,50, y=73,21, z=257,49], us['Stalfos Guard'/51, l='MpServer', x=544,50, y=84,00, z=239,50], ts['Falling Block'/187, l='MpServer', x=519,50, y=73,21, z=252,51], us['Stalfos Guard'/50, l='MpServer', x=544,50, y=69,00, z=225,50], ts['Falling Block'/184, l='MpServer', x=521,50, y=73,21, z=257,49], tv['entity.MinecartChest.name'/49, l='MpServer', x=555,50, y=34,50, z=192,50], ts['Falling Block'/185, l='MpServer', x=519,50, y=73,21, z=252,51], uc['entity.MinecartTNT.name'/55, l='MpServer', x=551,50, y=65,50, z=256,50], us['Stalfos Guard'/54, l='MpServer', x=552,50, y=94,00, z=255,50], ug['Creeper'/53, l='MpServer', x=549,50, y=63,00, z=255,50], tv['entity.MinecartChest.name'/52, l='MpServer', x=551,50, y=29,50, z=245,50], ts['Falling Block'/178, l='MpServer', x=521,50, y=73,21, z=257,49], ts['Falling Block'/179, l='MpServer', x=519,50, y=73,21, z=252,51], tv['entity.MinecartChest.name'/58, l='MpServer', x=554,50, y=25,50, z=332,50], ts['Falling Block'/176, l='MpServer', x=521,50, y=72,48, z=258,71], us['Stalfos Guard'/57, l='MpServer', x=544,50, y=69,00, z=284,50], ts['Falling Block'/177, l='MpServer', x=519,50, y=72,48, z=251,29], uc['entity.MinecartTNT.name'/56, l='MpServer', x=551,50, y=65,50, z=256,50], ts['Falling Block'/182, l='MpServer', x=521,50, y=73,21, z=257,49], ts['Falling Block'/183, l='MpServer', x=519,50, y=73,21, z=252,51], ts['Falling Block'/180, l='MpServer', x=521,50, y=73,21, z=257,49], ts['Falling Block'/181, l='MpServer', x=519,50, y=73,21, z=252,51], ts['Falling Block'/207, l='MpServer', x=519,50, y=73,19, z=257,10], ts['Falling Block'/206, l='MpServer', x=521,50, y=73,19, z=252,90], tv['entity.MinecartChest.name'/64, l='MpServer', x=563,50, y=30,34, z=225,50], ts['Falling Block'/203, l='MpServer', x=519,50, y=73,38, z=256,60], ts['Falling Block'/202, l='MpServer', x=521,50, y=73,38, z=253,40], bgh['Daniel_Mestre'/74, l='MpServer', x=494,43, y=69,62, z=254,89], ts['Falling Block'/218, l='MpServer', x=521,50, y=70,57, z=249,09], ts['Falling Block'/219, l='MpServer', x=519,50, y=70,57, z=260,91], ts['Falling Block'/214, l='MpServer', x=521,50, y=71,56, z=250,23], ts['Falling Block'/215, l='MpServer', x=519,50, y=71,56, z=259,77], ts['Falling Block'/210, l='MpServer', x=521,50, y=71,98, z=250,79], ts['Falling Block'/211, l='MpServer', x=519,50, y=71,98, z=259,21], ts['Falling Block'/102, l='MpServer', x=521,50, y=69,58, z=261,25], ts['Falling Block'/103, l='MpServer', x=519,50, y=69,58, z=248,75], ts['Falling Block'/100, l='MpServer', x=521,50, y=69,49, z=261,59], ts['Falling Block'/101, l='MpServer', x=519,50, y=69,49, z=248,41]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bgc.a(SourceFile:297)
	at awp.b(SourceFile:1874)
	at awp.e(SourceFile:686)
	at net.minecraft.client.main.Main.main(SourceFile:104)

-- System Details --
Details:
	Minecraft Version: 13w38c
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 43600256 bytes (41 MB) / 162058240 bytes (154 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 13859 (776104 bytes; 0 MB) allocated, 275 (15400 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 13w38c
	LWJGL: 2.9.0
	OpenGL: GeForce G 103M/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: [Resource Pack]
	Current Language: English (UK)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1290 (72240 bytes; 0 MB) allocated, 208 (11648 bytes; 0 MB) used