I was crafting a level 3/4 map into a level 4/4 map, and in the tooltip said "Unknown map" when I grabbed it from the crafting table, it crashed my client. This was on a bukkit server.

---- Minecraft Crash Report ----
// Why did you do that?

Time: 04/01/14 20:36
Description: Updating screen events

java.lang.NullPointerException: Updating screen events
at aby.d(SourceFile:221)
at abu.a(SourceFile:336)
at zo.b(SourceFile:41)
at zo.a(SourceFile:58)
at yj.a(SourceFile:238)
at bjz.a(SourceFile:308)
at bdn.a(SourceFile:490)
at bdn.a(SourceFile:318)
at bcl.d(SourceFile:232)
at bcl.k(SourceFile:211)
at azi.p(SourceFile:1308)
at azi.ah(SourceFile:760)
at azi.f(SourceFile:711)
at net.minecraft.client.main.Main.main(SourceFile:152)

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

– Head –
Stacktrace:
at aby.d(SourceFile:221)
at abu.a(SourceFile:336)
at zo.b(SourceFile:41)
at zo.a(SourceFile:58)
at yj.a(SourceFile:238)
at bjz.a(SourceFile:308)
at bdn.a(SourceFile:490)
at bdn.a(SourceFile:318)
at bcl.d(SourceFile:232)
at bcl.k(SourceFile:211)

– Affected screen –
Details:
Screen name: bdz

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bkf['chilbree'/152635, l='MpServer', x=-545.04, y=176.73, z=749.77]]
Chunk stats: MultiplayerChunkCache: 318, 318
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (-1516,58,265), Chunk: (at 4,3,9 in -95,16; contains blocks -1520,0,256 to -1505,255,271), Region: (-3,0; contains chunks -96,0 to -65,31, blocks -1536,0,0 to -1025,255,511)
Level time: 22702993 game time, 672000 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: true), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Forced entities: 1 total; [bkf['chilbree'/152635, l='MpServer', x=-545.04, y=176.73, z=749.77]]
Retry entities: 0 total; []
Server brand: CraftBukkit
Server type: Non-integrated multiplayer server
Stacktrace:
at bka.a(SourceFile:289)
at azi.b(SourceFile:1952)
at azi.f(SourceFile:720)
at net.minecraft.client.main.Main.main(SourceFile:152)

– System Details –
Details:
Minecraft Version: 1.7.4
Operating System: Windows 8 (x86) version 6.2
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 134945040 bytes (128 MB) / 244797440 bytes (233 MB) up to 1037959168 bytes (989 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
AABB Pool Size: 2850 (159600 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 1.7.4
LWJGL: 2.9.1
OpenGL: AMD Radeon HD 7500G GL version 4.2.11764 Compatibility Profile Context, ATI Technologies Inc.
GL Caps: Using GL 1.3 multitexturing.
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: [Classic Sounds, faithful32pack]
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 51 (2856 bytes; 0 MB) allocated, 16 (896 bytes; 0 MB) used
Anisotropic Filtering: Off (1)