I'm past in 16 chunks and my game crashed.
The game say :
---- Minecraft Crash Report ----
// There are four lights!

Time: 23/07/14 16:31
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
at brj.b(SourceFile:28)
at cms.a(SourceFile:27)
at cjg.a(SourceFile:45)
at cit.a(SourceFile:465)
at cit.a(SourceFile:658)
at cho.a(SourceFile:1170)
at cho.a(SourceFile:1117)
at cho.b(SourceFile:970)
at brk.ar(SourceFile:900)
at brk.a(SourceFile:310)
at net.minecraft.client.main.Main.main(SourceFile:120)

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

– Head –
Stacktrace:
at brj.b(SourceFile:28)
at cms.a(SourceFile:27)
at cjg.a(SourceFile:45)
at cit.a(SourceFile:465)
at cit.a(SourceFile:658)
at cho.a(SourceFile:1170)
at cho.a(SourceFile:1117)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [cgv['timaultdu80'/18735, l='MpServer', x=431,83, y=91,99, z=46,12]]
Chunk stats: MultiplayerChunkCache: 567, 567
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: 54,00,64,00,276,00 - World: (54,64,276), Chunk: (at 6,4,4 in 3,17; contains blocks 48,0,272 to 63,255,287), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 12605 game time, 19907 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: 65 total; [afb['Skeleton'/197381, l='MpServer', x=479,50, y=72,19, z=78,50], adv['Creeper'/193524, l='MpServer', x=364,66, y=74,00, z=-22,50], afj['Spider'/197380, l='MpServer', x=479,50, y=72,02, z=78,50], afj['Spider'/197382, l='MpServer', x=479,50, y=72,02, z=83,50], adv['Creeper'/197376, l='MpServer', x=481,09, y=72,00, z=78,50], adv['Creeper'/192031, l='MpServer', x=367,50, y=71,00, z=112,50], adx['Enderman'/193530, l='MpServer', x=359,50, y=75,00, z=-21,50], afb['Skeleton'/196403, l='MpServer', x=499,50, y=41,00, z=39,50], afb['Skeleton'/189870, l='MpServer', x=405,50, y=72,00, z=36,50], afo['Zombie'/194476, l='MpServer', x=460,69, y=41,00, z=70,50], adv['Creeper'/189865, l='MpServer', x=395,50, y=72,00, z=30,50], adv['Creeper'/199562, l='MpServer', x=463,50, y=26,02, z=40,50], afo['Zombie'/194478, l='MpServer', x=458,53, y=41,00, z=66,88], afo['Zombie'/196407, l='MpServer', x=500,50, y=41,00, z=37,50], afo['Zombie'/199555, l='MpServer', x=465,50, y=26,02, z=52,50], adv['Creeper'/186059, l='MpServer', x=362,50, y=69,00, z=89,50], afb['Skeleton'/192053, l='MpServer', x=406,47, y=69,00, z=13,88], abf['Bat'/196097, l='MpServer', x=476,49, y=40,86, z=50,44], afo['Zombie'/192034, l='MpServer', x=377,06, y=71,00, z=113,41], abf['Bat'/196096, l='MpServer', x=468,42, y=41,81, z=64,24], abf['Bat'/196098, l='MpServer', x=478,22, y=40,04, z=49,07], afb['Skeleton'/199594, l='MpServer', x=377,50, y=71,02, z=-26,50], cgv['timaultdu80'/18735, l='MpServer', x=431,83, y=91,99, z=46,12], afj['Spider'/192042, l='MpServer', x=390,16, y=72,00, z=22,97], afj['Spider'/192043, l='MpServer', x=396,59, y=71,00, z=23,59], afj['Spider'/192041, l='MpServer', x=369,09, y=71,00, z=102,19], afb['Skeleton'/192069, l='MpServer', x=402,50, y=63,00, z=110,50], adv['Creeper'/194575, l='MpServer', x=407,59, y=70,00, z=8,88], afb['Skeleton'/192071, l='MpServer', x=402,50, y=63,00, z=112,50], adv['Creeper'/194564, l='MpServer', x=418,69, y=69,00, z=8,22], adv['Creeper'/194567, l='MpServer', x=420,50, y=69,00, z=6,50], afb['Skeleton'/190915, l='MpServer', x=416,50, y=69,00, z=11,50], afb['Skeleton'/190914, l='MpServer', x=417,50, y=69,00, z=15,50], adv['Creeper'/188125, l='MpServer', x=372,78, y=71,00, z=110,16], afb['Skeleton'/190912, l='MpServer', x=419,50, y=69,00, z=18,50], abf['Bat'/192609, l='MpServer', x=420,75, y=39,03, z=33,75], abf['Bat'/195053, l='MpServer', x=454,47, y=39,92, z=67,44], afb['Skeleton'/190931, l='MpServer', x=360,50, y=34,00, z=-5,50], afn['Witch'/199222, l='MpServer', x=352,50, y=34,02, z=80,50], afo['Zombie'/199458, l='MpServer', x=363,50, y=39,02, z=-8,50], abf['Bat'/192624, l='MpServer', x=366,89, y=23,69, z=89,72], abf['Bat'/192628, l='MpServer', x=354,22, y=28,22, z=81,58], abf['Bat'/202113, l='MpServer', x=478,50, y=19,00, z=43,50], abf['Bat'/202115, l='MpServer', x=480,50, y=19,00, z=49,50], afj['Spider'/197581, l='MpServer', x=400,50, y=71,02, z=63,50], afo['Zombie'/191371, l='MpServer', x=382,69, y=71,00, z=117,13], adv['Creeper'/198543, l='MpServer', x=436,50, y=20,02, z=101,50], afo['Zombie'/196340, l='MpServer', x=429,59, y=25,00, z=113,09], afo['Zombie'/191373, l='MpServer', x=379,69, y=71,00, z=113,91], abf['Bat'/197804, l='MpServer', x=450,67, y=18,99, z=106,53], afo['Zombie'/190904, l='MpServer', x=417,53, y=69,00, z=7,88], abf['Bat'/201719, l='MpServer', x=469,50, y=30,00, z=4,50], afn['Witch'/198552, l='MpServer', x=437,49, y=20,00, z=100,63], afb['Skeleton'/195458, l='MpServer', x=376,50, y=72,00, z=-18,50], afb['Skeleton'/195456, l='MpServer', x=385,50, y=72,00, z=-22,50], afj['Spider'/198724, l='MpServer', x=510,50, y=84,00, z=-30,50], afb['Skeleton'/195462, l='MpServer', x=389,50, y=72,00, z=-17,50], abf['Bat'/185176, l='MpServer', x=356,15, y=35,38, z=76,96], abf['Bat'/200953, l='MpServer', x=473,71, y=45,01, z=36,53], adx['Enderman'/190323, l='MpServer', x=354,50, y=30,00, z=-19,50], afb['Skeleton'/193641, l='MpServer', x=397,50, y=66,00, z=-23,50], abf['Bat'/196091, l='MpServer', x=477,46, y=40,63, z=50,91], afb['Skeleton'/196564, l='MpServer', x=358,50, y=51,00, z=78,50], afb['Skeleton'/190075, l='MpServer', x=384,50, y=71,00, z=111,50], afj['Spider'/196562, l='MpServer', x=362,50, y=51,00, z=77,50]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at ccu.a(SourceFile:308)
at brk.b(SourceFile:2262)
at brk.a(SourceFile:324)
at net.minecraft.client.main.Main.main(SourceFile:120)

– System Details –
Details:
Minecraft Version: 14w30a
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.7.0_45, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 224078240 bytes (213 MB) / 703594496 bytes (671 MB) up to 954728448 bytes (910 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 14w30a
LWJGL: 2.9.1
OpenGL: AMD Radeon HD 7400 Series GL version 4.3.12618 Compatibility Profile Context 13.251.0.0, ATI Technologies Inc.
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.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
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)