Hopper: java.lang.NullPointerException: Ticking entity

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-1973138/

Crash:

java.lang.NullPointerException: Ticking entity
	at apf.b(SourceFile:222)
	at wv.a(SourceFile:1975)
	at ahn.a(SourceFile:35)
	at ahj.s_(SourceFile:148)
	at aqs.a(SourceFile:1406)
	at qt.a(SourceFile:601)
	at aqs.g(SourceFile:1384)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// But it works on my machine.

Time: 14-8-22 下午6:29
Description: Ticking entity

java.lang.NullPointerException: Ticking entity
	at apf.b(SourceFile:222)
	at wv.a(SourceFile:1975)
	at ahn.a(SourceFile:35)
	at ahj.s_(SourceFile:148)
	at aqs.a(SourceFile:1406)
	at qt.a(SourceFile:601)
	at aqs.g(SourceFile:1384)
	at aqs.i(SourceFile:1277)
	at qt.i(SourceFile:479)
	at net.minecraft.server.MinecraftServer.z(SourceFile:607)
	at net.minecraft.server.MinecraftServer.y(SourceFile:531)
	at cyf.y(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:447)
	at java.lang.Thread.run(Unknown Source)


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

-- Head --
Stacktrace:
	at apf.b(SourceFile:222)
	at wv.a(SourceFile:1975)
	at ahn.a(SourceFile:35)
	at ahj.s_(SourceFile:148)
	at aqs.a(SourceFile:1406)
	at qt.a(SourceFile:601)
	at aqs.g(SourceFile:1384)

-- Entity being ticked --
Details:
	Entity Type: SmallFireball (ahn)
	Entity ID: 35951
	Entity Name: 小火球
	Entity's Exact location: -913.34, 28.15, -239.50
	Entity's Block location: -914.00,28.00,-240.00 - World: (-914,28,-240), Chunk: (at 14,1,0 in -58,-15; contains blocks -928,0,-240 to -913,255,-225), Region: (-2,-1; contains chunks -64,-32 to -33,-1, blocks -1024,0,-512 to -513,255,-1)
	Entity's Momentum: -0.57, -0.01, -0.00
	Entity's Rider: ~~ERROR~~ NullPointerException: null
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at aqs.i(SourceFile:1277)
	at qt.i(SourceFile:479)

-- Affected level --
Details:
	Level name: Super Steve 3D Land -ST
	All players: 1 total; [qw['gsgdsaj'/477, l='Super Steve 3D Land -ST', x=-914.32, y=27.00, z=-239.35]]
	Chunk stats: ServerChunkCache: 870 Drop: 0
	Level seed: 7113018457721272765
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 3;minecraft:bedrock,10*minecraft:dirt,minecraft:grass;1;village
	Level spawn location: -364.00,5.00,-161.00 - World: (-364,5,-161), Chunk: (at 4,0,15 in -23,-11; contains blocks -368,0,-176 to -353,255,-161), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Level time: 3530288 game time, 1000 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 1 (now: false), thunder time: 1 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.z(SourceFile:607)
	at net.minecraft.server.MinecraftServer.y(SourceFile:531)
	at cyf.y(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:447)
	at java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
	Minecraft Version: 1.8-pre1
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_60, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 134281696 bytes (128 MB) / 408870912 bytes (389 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [qw['gsgdsaj'/477, l='Super Steve 3D Land -ST', x=-914.32, y=27.00, z=-239.35]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-1973138/70900564/