Minecraft crashed when making expanding map on server

-- Minecraft Crash Report ----
// My bad.

Time: 4/4/14 7:28 PM
Description: Updating screen events

java.lang.NullPointerException: Updating screen events
	at ace.d(SourceFile:221)
	at aca.a(SourceFile:336)
	at zu.b(SourceFile:41)
	at zu.a(SourceFile:58)
	at yp.a(SourceFile:238)
	at bkf.a(SourceFile:308)
	at bdq.a(SourceFile:490)
	at bdq.a(SourceFile:318)
	at bco.d(SourceFile:232)
	at bco.k(SourceFile:211)
	at azl.p(SourceFile:1303)
	at azl.ah(SourceFile:757)
	at azl.f(SourceFile:711)
	at net.minecraft.client.main.Main.main(SourceFile:148)


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

-- Head --
Stacktrace:
	at ace.d(SourceFile:221)
	at aca.a(SourceFile:336)
	at zu.b(SourceFile:41)
	at zu.a(SourceFile:58)
	at yp.a(SourceFile:238)
	at bkf.a(SourceFile:308)
	at bdq.a(SourceFile:490)
	at bdq.a(SourceFile:318)
	at bco.d(SourceFile:232)
	at bco.k(SourceFile:211)

-- Affected screen --
Details:
	Screen name: bec

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bkl['Em0k'/221741, l='MpServer', x=-378.70, y=81.62, z=1563.87]]
	Chunk stats: MultiplayerChunkCache: 441, 441
	Level seed: 0
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-379,79,1577), Chunk: (at 5,4,9 in -24,98; contains blocks -384,0,1568 to -369,255,1583), Region: (-1,3; contains chunks -32,96 to -1,127, blocks -512,0,1536 to -1,255,2047)
	Level time: 138597966 game time, 144399158 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: 66 total; [bkl['Em0k'/221741, l='MpServer', x=-378.70, y=81.62, z=1563.87], vd['Chicken'/221780, l='MpServer', x=-349.22, y=68.00, z=1569.78], vd['Chicken'/221781, l='MpServer', x=-349.22, y=68.00, z=1568.78], vd['Chicken'/221782, l='MpServer', x=-349.22, y=68.00, z=1569.22], vd['Chicken'/221783, l='MpServer', x=-349.22, y=68.00, z=1569.22], vd['Chicken'/221776, l='MpServer', x=-348.22, y=69.00, z=1582.22], vd['Chicken'/221777, l='MpServer', x=-349.22, y=68.00, z=1568.78], vd['Chicken'/221778, l='MpServer', x=-349.22, y=68.00, z=1569.78], vd['Chicken'/221779, l='MpServer', x=-349.22, y=68.00, z=1569.78], vd['Chicken'/221788, l='MpServer', x=-349.22, y=68.00, z=1568.78], vm['Sheep'/221789, l='MpServer', x=-341.06, y=69.00, z=1580.88], vm['jeb_'/221790, l='MpServer', x=-347.91, y=69.00, z=1573.44], vm['jeb_'/221791, l='MpServer', x=-335.69, y=69.00, z=1581.91], vd['Chicken'/221784, l='MpServer', x=-349.22, y=68.00, z=1569.78], vd['Chicken'/221785, l='MpServer', x=-349.22, y=68.00, z=1569.78], vd['Chicken'/221786, l='MpServer', x=-349.22, y=68.00, z=1569.22], vd['Chicken'/221787, l='MpServer', x=-349.22, y=68.00, z=1569.78], xn['Zombie'/221765, l='MpServer', x=-364.50, y=42.00, z=1525.50], vd['Chicken'/221764, l='MpServer', x=-367.38, y=12.00, z=1525.41], vd['Chicken'/221767, l='MpServer', x=-347.47, y=59.00, z=1576.63], xi['Skeleton'/221766, l='MpServer', x=-338.94, y=14.00, z=1572.59], vm['jeb_'/221761, l='MpServer', x=-344.78, y=69.00, z=1567.13], vm['jeb_'/221760, l='MpServer', x=-344.47, y=69.00, z=1574.08], ww['Creeper'/221763, l='MpServer', x=-393.50, y=14.00, z=1532.50], ww['Creeper'/221762, l='MpServer', x=-392.47, y=15.00, z=1530.00], vd['Chicken'/221773, l='MpServer', x=-348.22, y=69.00, z=1582.22], vd['Chicken'/221772, l='MpServer', x=-349.22, y=68.00, z=1569.78], vd['Chicken'/221775, l='MpServer', x=-349.22, y=68.00, z=1568.22], vd['Chicken'/221774, l='MpServer', x=-348.22, y=69.00, z=1582.22], vd['Chicken'/221769, l='MpServer', x=-340.66, y=59.00, z=1580.53], vd['Chicken'/221768, l='MpServer', x=-340.91, y=58.00, z=1582.63], vd['Chicken'/221771, l='MpServer', x=-349.22, y=68.00, z=1568.78], vd['Chicken'/221770, l='MpServer', x=-349.22, y=68.00, z=1568.22], vm['jeb_'/221814, l='MpServer', x=-360.47, y=11.00, z=1519.38], xk['Spider'/221811, l='MpServer', x=-380.50, y=31.00, z=1610.50], vm['Sheep'/221808, l='MpServer', x=-372.63, y=11.00, z=1517.25], vm['jeb_'/221820, l='MpServer', x=-344.44, y=69.00, z=1575.24], ve['Cow'/221821, l='MpServer', x=-334.03, y=69.00, z=1569.44], xk['Spider'/221819, l='MpServer', x=-331.50, y=34.00, z=1536.50], vm['jeb_'/221799, l='MpServer', x=-342.69, y=69.00, z=1565.16], vf['Horse'/221798, l='MpServer', x=-347.66, y=69.00, z=1572.00], vm['Sheep'/221797, l='MpServer', x=-348.56, y=73.00, z=1568.34], vm['jeb_'/221796, l='MpServer', x=-344.41, y=69.00, z=1574.06], vf['Horse'/221795, l='MpServer', x=-338.78, y=69.00, z=1579.72], wh['item.item.egg'/221794, l='MpServer', x=-349.97, y=68.13, z=1568.25], vm['jeb_'/221793, l='MpServer', x=-345.53, y=69.00, z=1570.63], vm['jeb_'/221792, l='MpServer', x=-348.88, y=70.50, z=1570.03], ww['Creeper'/221804, l='MpServer', x=-349.50, y=38.00, z=1528.50], ww['Creeper'/221803, l='MpServer', x=-342.50, y=31.00, z=1528.50], vm['Sheep'/221802, l='MpServer', x=-364.50, y=63.00, z=1587.94], xn['Zombie'/221801, l='MpServer', x=-367.91, y=16.00, z=1589.25], ww['Creeper'/221800, l='MpServer', x=-361.59, y=15.00, z=1600.00], xi['Skeleton'/221835, l='MpServer', x=-342.50, y=42.00, z=1610.50], xi['Skeleton'/221826, l='MpServer', x=-333.50, y=22.00, z=1593.50], xn['Zombie'/221827, l='MpServer', x=-331.50, y=22.00, z=1593.50], xz['arrow'/221887, l='MpServer', x=-335.41, y=71.03, z=1622.94], xi['Skeleton'/221751, l='MpServer', x=-389.59, y=48.00, z=1558.50], ww['Creeper'/221754, l='MpServer', x=-353.50, y=34.00, z=1548.50], xi['Skeleton'/221755, l='MpServer', x=-403.50, y=25.00, z=1557.50], xk['Spider'/221752, l='MpServer', x=-381.00, y=16.00, z=1572.16], vd['Chicken'/221753, l='MpServer', x=-397.84, y=62.37, z=1541.53], vd['Chicken'/221879, l='MpServer', x=-420.47, y=70.00, z=1524.38], vd['Chicken'/221758, l='MpServer', x=-349.22, y=73.00, z=1566.78], vm['jeb_'/221759, l='MpServer', x=-345.91, y=73.00, z=1564.50], wh['item.item.rottenFlesh'/221756, l='MpServer', x=-401.03, y=63.63, z=1552.84], wh['item.item.egg'/221757, l='MpServer', x=-381.13, y=66.13, z=1534.03]]
	Retry entities: 0 total; []
	Server brand: CraftBukkit
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bkg.a(SourceFile:289)
	at azl.b(SourceFile:1947)
	at azl.f(SourceFile:720)
	at net.minecraft.client.main.Main.main(SourceFile:148)

-- System Details --
Details:
	Minecraft Version: 1.7.5
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 61293432 bytes (58 MB) / 166096896 bytes (158 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 1.7.5
	LWJGL: 2.9.1
	OpenGL: AMD Radeon HD 7560D GL version 4.2.11472 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: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Anisotropic Filtering: Off (1)