When player joined, server immediatelly crashes.

log:
<pre>
[12:12:29] [Server thread/INFO]: Preparing start region for level 0
[12:12:31] [Server thread/INFO]: Preparing spawn area: 0%
[12:12:32] [Server thread/INFO]: Done (3.032s)! For help, type "help" or "?"
[12:13:48] User Authenticator #1/INFO: UUID of player HunterzCZ is fb2fe292-eec8-4daa-b7b3-d1ff848111d0
[12:13:48] [Server thread/WARN]: Ignored advancement 'minecraft:recipes/transportation/boat' in progress file ./world/advancements/fb2fe292-eec8-4daa-b7b3-d1ff848111d0.json - it doesn't exist anymore?
[12:13:48] [Server thread/INFO]: Tried to load unrecognized recipe: minecraft:boat removed now.
[12:13:48] [Server thread/INFO]: Tried to load unrecognized recipe: minecraft:boat removed now.
[12:13:48] [Server thread/INFO]: TextComponent{text='HunterzCZ', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}[/62.182.23
[12:13:48] [Server thread/INFO]: HunterzCZ joined the game
[12:13:48] [Server thread/ERROR]: Encountered an unexpected exception
java.lang.NullPointerException: null
at hk.hashCode(SourceFile:121) ~[minecraft_server.18w01a.jar:?]
at java.util.HashMap.hash(HashMap.java:338) ~[?:1.8.0_74]
at java.util.HashMap.remove(HashMap.java:798) ~[?:1.8.0_74]
at bjy.a(SourceFile:143) ~[minecraft_server.18w01a.jar:?]
at rr.a(SourceFile:168) ~[minecraft_server.18w01a.jar:?]
at rk.a(SourceFile:202) ~[minecraft_server.18w01a.jar:?]
at net.minecraft.server.MinecraftServer.w(SourceFile:687) ~[minecraft_server.18w01a.jar:?]
at qy.w(SourceFile:352) ~[minecraft_server.18w01a.jar:?]
at net.minecraft.server.MinecraftServer.v(SourceFile:604) ~[minecraft_server.18w01a.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:509) [minecraft_server.18w01a.jar:?]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_74]
[12:13:48] [Server thread/ERROR]: This crash report has been saved to: /home/bukkit/vanilka/./crash-reports/crash-2018-01-06_12.13.48-server.txt
</pre>

crashlog:
<pre>
---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 1/6/18 12:13 PM
Description: Exception in server tick loop

java.lang.NullPointerException: Exception in server tick loop
at hk.hashCode(SourceFile:121)
at java.util.HashMap.hash(HashMap.java:338)
at java.util.HashMap.remove(HashMap.java:798)
at bjy.a(SourceFile:143)
at rr.a(SourceFile:168)
at rk.a(SourceFile:202)
at net.minecraft.server.MinecraftServer.w(SourceFile:687)
at qy.w(SourceFile:352)
at net.minecraft.server.MinecraftServer.v(SourceFile:604)
at net.minecraft.server.MinecraftServer.run(SourceFile:509)
at java.lang.Thread.run(Thread.java:745)

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

– System Details –
Details:
Minecraft Version: 18w01a
Operating System: Linux (amd64) version 4.7.2-101.fc23.x86_64
Java Version: 1.8.0_74, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 262713008 bytes (250 MB) / 722857984 bytes (689 MB) up to 2077753344 bytes (1981 MB)
JVM Flags: 2 total; -Xmx2G -Xincgc
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Profiler Position: N/A (disabled)
Player Count: 1 / 20; [rp['TextComponent{text='HunterzCZ', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}'/229, l=
Data Packs: vanilla
Is Modded: Unknown (can't tell)
Type: Dedicated Server (map_server.txt)
</pre>