Minecraft Crash beim joinen auf die Map

-- Head --
Stacktrace:
        at aaa.a(SourceFile:44)
        at zu.m(SourceFile:117)
        at ahn.a(SourceFile:1467)
        at lp.a(SourceFile:719)
        at ahn.g(SourceFile:1445)


-- Entity being ticked --
Details:
        Entity Type: SmallFireball (aaa)
        Entity ID: 412
        Entity Name: Small Fireball
        Entity's Exact location: 87.46, 62.40, -20.21
        Entity's Block location: World: (87,62,-21), Chunk: (at 7,3,11 in 5,-2; contains blocks 80,0,-32 to 95,255,-17), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
        Entity's Momentum: -0.89, -0.08, 0.87
        Entity's Passengers: []
        Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
        at ahn.k(SourceFile:1335)
        at lp.k(SourceFile:552)


-- Affected level --
Details:
        Level name: world
        All players: 1 total; [lr['Wythe'/397, l='world', x=87.78, y=61.00, z=-19.17]]
        Chunk stats: ServerChunkCache: 443 Drop: 0
        Level seed: -4464162308503575534
        Level generator: ID 00 - default, ver 1. Features enabled: false
        Level generator options:
        Level spawn location: World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
        Level time: 0 game time, 0 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: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
        at net.minecraft.server.MinecraftServer.D(SourceFile:625)
        at la.D(SourceFile:339)
        at net.minecraft.server.MinecraftServer.C(SourceFile:553)
        at net.minecraft.server.MinecraftServer.run(SourceFile:457)
        at java.lang.Thread.run(Thread.java:745)


-- System Details --
Details:
        Minecraft Version: 15w49b
        Operating System: Linux (amd64) version 3.2.0-4-amd64
        Java Version: 1.7.0_79, Oracle Corporation
        Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
        Memory: 1538579856 bytes (1467 MB) / 1723203584 bytes (1643 MB) up to 1723203584 bytes (1643 MB)
        JVM Flags: 2 total; -Xmx1700M -Xms1700M
        IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 98
        Profiler Position: N/A (disabled)
        Player Count: 1 / 20; [lr['Wythe'/397, l='world', x=87.78, y=61.00, z=-19.17]]
        Is Modded: Unknown (can't tell)
        Type: Dedicated Server (map_server.txt)