Put the summary of the bug you're having here

*What I expected to happen was the world to load up fine.
Describe what you thought should happen here

*What actually happened was the world crashed.
Describe what happened here

Steps to Reproduce:
1. Generate an old world (1.5-1.6 I believe)
2. Load up that world in 1.8 or snapshot.
3. Watch it crash.
(If you need the world I tried tell me how to put it up for download and I will do it for you guys)
Crash Report:
---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 5/2/14 3:53 PM
Description: Rendering entity in world

java.lang.NullPointerException: Rendering entity in world
at cce.a(SourceFile:79)
at cce.a(SourceFile:51)
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:937)
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:51)
at cce.a(SourceFile:24)

– Entity being rendered –
Details:
Entity Type: ItemFrame (uh)
Entity ID: 715
Entity Name: entity.ItemFrame.name
Entity's Exact location: 879.03, 72.50, -225.50
Entity's Block location: 879.00,72.00,-226.00 - World: (879,72,-226), Chunk: (at 15,4,14 in 54,-15; contains blocks 864,0,-240 to 879,255,-225), Region: (1,-1; contains chunks 32,-32 to 63,-1, blocks 512,0,-512 to 1023,255,-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@7711a38f
Location: 48.00,-47.00,28.61 - World: (47,-47,28), Chunk: (at 15,-3,12 in 2,1; contains blocks 32,0,16 to 47,255,31), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Rotation: 270.0
Delta: 0.09157407
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['Supercrafter90'/615, l='MpServer', x=831.03, y=119.50, z=-254.11]]
Chunk stats: MultiplayerChunkCache: 30, 30
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: 156.00,64.00,60.00 - World: (156,64,60), Chunk: (at 12,4,12 in 9,3; contains blocks 144,0,48 to 159,255,63), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 3496968 game time, 2050 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: 29 total; [abq['testificate'/687, l='MpServer', x=842.34, y=66.00, z=-269.47], abq['testifcate'/611, l='MpServer', x=815.16, y=63.00, z=-283.56], yj['Pig'/686, l='MpServer', x=837.98, y=70.00, z=-277.53], abq['Passenger'/614, l='MpServer', x=804.50, y=83.00, z=-287.13], abq['testifcate'/612, l='MpServer', x=813.84, y=65.00, z=-279.44], yj['Pig'/613, l='MpServer', x=808.00, y=66.00, z=-280.97], yj['Pig'/679, l='MpServer', x=806.21, y=63.00, z=-216.47], abq['testificate'/678, l='MpServer', x=808.64, y=85.00, z=-237.88], yp['Iron Golem'/677, l='MpServer', x=784.31, y=93.00, z=-221.50], ya['Chicken'/676, l='MpServer', x=785.38, y=93.00, z=-222.94], yk['Sheep'/675, l='MpServer', x=786.47, y=93.00, z=-215.28], yk['Sheep'/674, l='MpServer', x=786.91, y=93.00, z=-222.75], yp['Iron Golem'/673, l='MpServer', x=784.94, y=93.00, z=-214.81], yj['Pig'/672, l='MpServer', x=786.06, y=93.00, z=-211.34], ya['Chicken'/690, l='MpServer', x=832.47, y=65.00, z=-267.75], yk['Sheep'/691, l='MpServer', x=832.53, y=61.50, z=-216.56], abq['testificate'/688, l='MpServer', x=836.34, y=64.00, z=-267.31], yj['Pig'/689, l='MpServer', x=842.44, y=70.00, z=-264.72], uh['entity.ItemFrame.name'/715, l='MpServer', x=879.03, y=72.50, z=-225.50], uh['entity.ItemFrame.name'/714, l='MpServer', x=879.50, y=72.50, z=-226.97], abq['Space Station Owner'/717, l='MpServer', x=872.50, y=71.00, z=-213.50], uh['entity.ItemFrame.name'/716, l='MpServer', x=879.03, y=72.50, z=-224.50], bxb['Supercrafter90'/615, l='MpServer', x=831.03, y=119.50, z=-254.11], ya['Chicken'/668, l='MpServer', x=787.22, y=93.00, z=-224.25], yk['Sheep'/669, l='MpServer', x=785.47, y=93.00, z=-209.94], ya['Chicken'/670, l='MpServer', x=787.75, y=93.00, z=-214.53], yk['Sheep'/671, l='MpServer', x=785.84, y=93.00, z=-223.94], yj['Pig'/666, l='MpServer', x=796.09, y=68.00, z=-268.94], yj['Pig'/667, l='MpServer', x=799.53, y=68.00, z=-230.72]]
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: Mac OS X (x86_64) version 10.9.2
Java Version: 1.6.0_65, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 112798624 bytes (107 MB) / 386306048 bytes (368 MB) up to 4277534720 bytes (4079 MB)
JVM Flags: 1 total; -Xmx4G
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 14w18a
LWJGL: 2.9.1
OpenGL: Intel HD Graphics 4000 OpenGL Engine GL version 2.1 INTEL-8.24.12, Intel 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.
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: []
Current Language: English (US)
Profiler Position: N/A (disabled)
Anisotropic Filtering: Off (1)