When placing an item frame, the world crashes and then will continue to crash whenever being opened.
The description in the launcher following the crash is as follows.

---- Minecraft Crash Report ----
// I feel sad now

Time: 01/05/14 20:13
Description: Rendering entity in world

java.lang.NullPointerException: Rendering entity in world
at cce.a(SourceFile:79)
at cce.a(SourceFile:53)
at cce.a(SourceFile:24)
at cbt.a(SourceFile:219)
at cbt.a(SourceFile:199)
at cbt.a(SourceFile:176)
at bxs.a(SourceFile:495)
at bxl.a(SourceFile:1146)
at bxl.b(SourceFile:935)
at bjf.ai(SourceFile:828)
at bjf.f(SourceFile:755)
at net.minecraft.client.main.Main.main(SourceFile:121)

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

– Head –
Stacktrace:
at cce.a(SourceFile:79)
at cce.a(SourceFile:53)
at cce.a(SourceFile:24)

– Entity being rendered –
Details:
Entity Type: ItemFrame (uh)
Entity ID: 52
Entity Name: entity.ItemFrame.name
Entity's Exact location: 507.50, 58.50, -232.03
Entity's Block location: 507.00,58.00,-233.00 - World: (507,58,-233), Chunk: (at 11,3,7 in 31,-15; contains blocks 496,0,-240 to 511,255,-225), 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
Entity's Rider: ~_ERROR~ NullPointerException: null
Entity's Vehicle: ~_ERROR~ NullPointerException: null

– Renderer details –
Details:
Assigned renderer: cce@7fa7fa99
Location: -0.27,1.24,2.68 - World: (-1,1,2), Chunk: (at 15,0,2 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)
Rotation: 180.0
Delta: 0.97448635
Stacktrace:
at cbt.a(SourceFile:219)
at cbt.a(SourceFile:199)
at cbt.a(SourceFile:176)
at bxs.a(SourceFile:495)
at bxl.a(SourceFile:1146)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bxb['Dwittyy'/51, l='MpServer', x=507.77, y=57.26, z=-234.71]]
Chunk stats: MultiplayerChunkCache: 5, 5
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: 469.00,4.00,-568.00 - World: (469,4,-568), Chunk: (at 5,0,8 in 29,-36; contains blocks 464,0,-576 to 479,255,-561), Region: (0,-2; contains chunks 0,-64 to 31,-33, blocks 0,0,-1024 to 511,255,-513)
Level time: 5147920 game time, 7337 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: 2 total; [bxb['Dwittyy'/51, l='MpServer', x=507.77, y=57.26, z=-234.71], uh['entity.ItemFrame.name'/52, l='MpServer', x=507.50, y=58.50, z=-232.03]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at buw.a(SourceFile:308)
at bjf.b(SourceFile:2069)
at bjf.f(SourceFile:764)
at net.minecraft.client.main.Main.main(SourceFile:121)

– System Details –
Details:
Minecraft Version: 14w18a
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 158035408 bytes (150 MB) / 566689792 bytes (540 MB) up to 954466304 bytes (910 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 14w18a
LWJGL: 2.9.1
OpenGL: GeForce GT 630/PCIe/SSE2 GL version 4.2.0, 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.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: [HD FONT.zip]
Current Language: English (UK)
Profiler Position: N/A (disabled)
Anisotropic Filtering: Off (1)