Reproduce: I don't now. I am working on Iron Golem farm. I left the game and when I trying to join my game crashed and still crashing.

• ---- Minecraft Crash Report -------- Minecraft Crash Report ----// Hey, that tickles! Hehehe!
  Time: 25.2.19 22:56Description: Ticking entity
  java.lang.NullPointerException: Ticking entity at ahw.a(SourceFile:1049) at ahw.dD(SourceFile:1038) at aic.dD(SourceFile:35) at ahw.h(SourceFile:289) at anw.h(SourceFile:573) at aod.h(SourceFile:83) at uv.a(SourceFile:565) at uv$$Lambda$2583/1175386065.accept(Unknown Source) at bdf.a(SourceFile:683) at uv.a(SourceFile:368) at net.minecraft.server.MinecraftServer.b(SourceFile:837) at net.minecraft.server.MinecraftServer.a(SourceFile:776) at dtd.a(SourceFile:128) at net.minecraft.server.MinecraftServer.run(SourceFile:634) at java.lang.Thread.run(Thread.java:745)A detailed walkthrough of the error, its code path and all known details is as follows:---------------------------------------------------------------------------------------
  -- Head --Thread: Server threadStacktrace: at ahw.a(SourceFile:1049) at ahw.dD(SourceFile:1038) at aic.dD(SourceFile:35) at ahw.h(SourceFile:289) at anw.h(SourceFile:573) at aod.h(SourceFile:83) at uv.a(SourceFile:565) at uv$$Lambda$2583/1175386065.accept(Unknown Source)
  -- Entity being ticked --Details: Entity Type: minecraft:trader_llama (aod) Entity ID: 564 Entity Name: Obchodníkova lama Entity's Exact location: -1354.50, 88.00, -2833.37 Entity's Block location: World: (-1355,88,-2834), Chunk: (at 5,5,14 in -85,-178; contains blocks -1360,0,-2848 to -1345,255,-2833), Region: (-3,-6; contains chunks -96,-192 to -65,-161, blocks -1536,0,-3072 to -1025,255,-2561) Entity's Momentum: 0.01, -0.08, -0.03 Entity's Passengers: [] Entity's Vehicle: ~~ERROR~~ NullPointerException: nullStacktrace: at bdf.a(SourceFile:683) at uv.a(SourceFile:368)
  -- Affected level --Details: Level name: §6Ondra All players: 1 total; [uw['Ondra3211'/330, l='§6Ondra', x=-1358.12, y=77.00, z=-2816.58]] Chunk stats: ServerChunkCache: 2985 Level seed: 3373580655595963154 Level generator: ID 00 - default, ver 1. Features enabled: true Level generator options: {} Level spawn location: World: (0,64,176), Chunk: (at 0,4,0 in 0,11; contains blocks 0,0,176 to 15,255,191), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511) Level time: 8279182 game time, 9515335 day time Level dimension: 0 Level storage version: 0x04ABD - Anvil Level weather: Rain time: 134499 (now: false), thunder time: 16133 (now: false) Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: falseStacktrace: at net.minecraft.server.MinecraftServer.b(SourceFile:837) at net.minecraft.server.MinecraftServer.a(SourceFile:776) at dtd.a(SourceFile:128) at net.minecraft.server.MinecraftServer.run(SourceFile:634) at java.lang.Thread.run(Thread.java:745)
  -- System Details --Details: Minecraft Version: 19w08b Operating System: Windows 10 (amd64) version 10.0 Java Version: 1.8.0_51, Oracle Corporation Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation Memory: 4085641832 bytes (3896 MB) / 6006243328 bytes (5728 MB) up to 8589934592 bytes (8192 MB) JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx8G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M Player Count: 1 / 8; [uw['Ondra3211'/330, l='§6Ondra', x=-1358.12, y=77.00, z=-2816.58]] Data Packs: vanilla Type: Integrated Server (map_client.txt) Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.