The world runs on a server. There are no mods installed.

I cannot say much about the reason for the crach. But it always happend when i was flying over or near by the ocean. There are empty chunks (wholes down to the void) that doesn't load anymore. When i login to an other location i can continue playing.

---- Minecraft Crash Report ----
// My bad.

Time: 5/16/18 10:57 AM
Description: Exception generating new chunk

java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: bound must be positive
at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895)
at si.c(SourceFile:130)
at sq.a(SourceFile:84)
at sr.c(SourceFile:143)
at sj.i_(SourceFile:223)
at net.minecraft.server.MinecraftServer.w(SourceFile:689)
at ru.w(SourceFile:365)
at net.minecraft.server.MinecraftServer.v(SourceFile:622)
at net.minecraft.server.MinecraftServer.run(SourceFile:527)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.IllegalArgumentException: bound must be positive
at java.util.Random.nextInt(Random.java:388)
at bzs.a(SourceFile:203)
at bzu.a(SourceFile:186)
at bzu.a(SourceFile:182)
at bzj.a(SourceFile:59)
at byz$a.a(SourceFile:266)
at bzh.a(SourceFile:60)
at bvq.a(SourceFile:90)
at bxw.a(SourceFile:16)
at bxw.a(SourceFile:13)
at brt.a(SourceFile:27)
at bbv.a(SourceFile:515)
at bpg.a(SourceFile:109)
at sx.a(SourceFile:12)
at sw.a(SourceFile:33)
at bpk.a(SourceFile:85)
at tc.a(SourceFile:59)
at tc.a(SourceFile:23)
at agd$a.a(SourceFile:143)
at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:602)
at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:577)
at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:443)
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

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

– Head –
Thread: Server thread
Stacktrace:
at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)

– Chunk to be generated –
Details:
Location: 46,79
Position hash: 339302416430
Generator: brb@699a6f0c
Stacktrace:
at si.a(SourceFile:180)
at si.c(SourceFile:133)
at sq.a(SourceFile:84)
at sr.c(SourceFile:143)
at sj.i_(SourceFile:223)
at net.minecraft.server.MinecraftServer.w(SourceFile:689)
at ru.w(SourceFile:365)
at net.minecraft.server.MinecraftServer.v(SourceFile:622)
at net.minecraft.server.MinecraftServer.run(SourceFile:527)
at java.lang.Thread.run(Thread.java:748)

– Affected level –
Details:
Level name: Summertime
All players: 1 total; [sl['Frajac'/108, l='Summertime', x=623.05, y=84.78, z=1161.39]]
Chunk stats: ServerChunkCache: 690 Drop: 0
Level seed: 1792278300
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options: {}
Level spawn location: World: (96,67,-256), Chunk: (at 0,4,0 in 6,-16; contains blocks 96,0,-256 to 111,255,-241), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
Level time: 1271697 game time, 1157055 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 13866 (now: false), thunder time: 24500 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false

– System Details –
Details:
Minecraft Version: 18w20a
Operating System: Linux (amd64) version 3.13.0-143-generic
Java Version: 1.8.0_161, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1903030904 bytes (1814 MB) / 2178416640 bytes (2077 MB) up to 3817865216 bytes (3641 MB)
JVM Flags: 3 total; -Xms1024M -Xmx4096M -XX:MaxPermSize=256M
Profiler Position: N/A (disabled)
Player Count: 1 / 20; [sl['Frajac'/108, l='Summertime', x=623.05, y=84.78, z=1161.39]]
Data Packs: vanilla
Is Modded: Unknown (can't tell)
Type: Dedicated Server (map_server.txt)