I am exploring in a boat, the teacher is coming so I quickly quit Minecraft. When he leaves, I try to get back on but the game crashes as soon as I load the world. It shows me in the boat then crashes. Do not say anything about karma. This only happens when I immediately open the game menu when joining

Here is the crash report:

---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 9/9/19, 8:35 AM
Description: Exception generating new chunk

java.util.ConcurrentModificationException
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1134)
at cjg.b(SourceFile:67)
at cjg.a(SourceFile:57)
at cii$a.a(SourceFile:101)
at cii$a.<init>(SourceFile:81)
at cii.a(SourceFile:66)
at cdw$a.a(SourceFile:64)
at bwz.a(SourceFile:187)
at bxd.d(SourceFile:52)
at bxd.a(SourceFile:217)
at us.a(SourceFile:542)
at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
at us.a(SourceFile:536)
at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1072)
at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478)
at uu.b(SourceFile:57)
at agn.e(SourceFile:83)
at agn.a(SourceFile:123)
at agn.run(SourceFile:91)
at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)

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

– Head –
Thread: Server thread
Stacktrace:
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1134)
at cjg.b(SourceFile:67)
at cjg.a(SourceFile:57)
at cii$a.a(SourceFile:101)
at cii$a.<init>(SourceFile:81)
at cii.a(SourceFile:66)
at cdw$a.a(SourceFile:64)
at bwz.a(SourceFile:187)
at bxd.d(SourceFile:52)
at bxd.a(SourceFile:217)

– Chunk to be generated –
Details:
Location: 115,6
Position hash: 25769803891
Generator: byw@717a6f2b
Stacktrace:
at us.a(SourceFile:542)
at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
at us.a(SourceFile:536)
at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1072)
at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478)
at uu.b(SourceFile:57)

– Player being ticked –
Details:
Entity Type: minecraft:player (vh)
Entity ID: 57
Entity Name: Asadefa
Entity's Exact location: 1706.81, 62.07, -132.13
Entity's Block location: World: (1706,62,-133), Chunk: (at 10,3,11 in 106,-9; contains blocks 1696,0,-144 to 1711,255,-129), Region: (3,-1; contains chunks 96,-32 to 127,-1, blocks 1536,0,-512 to 2047,255,-1)
Entity's Momentum: 0.00, 0.00, 0.00
Entity's Passengers: []
Entity's Vehicle: axo['Boat'/59, l='Ultra Survive', x=1706.81, y=62.52, z=-132.13]
Stacktrace:
at vh.i(SourceFile:446)
at vy.b(SourceFile:196)
at ja.a(SourceFile:243)
at vx.c(SourceFile:171)
at net.minecraft.server.MinecraftServer.b(SourceFile:842)
at net.minecraft.server.MinecraftServer.a(SourceFile:764)
at dxk.a(SourceFile:128)
at net.minecraft.server.MinecraftServer.run(SourceFile:632)
at java.base/java.lang.Thread.run(Thread.java:834)

– Ticking connection –
Details:
Connection: ja@2a523e2b

– System Details –
Details:
Minecraft Version: 1.14.2
Operating System: Linux (amd64) version 4.15.0-60-generic
Java Version: 11.0.4, Ubuntu
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode, sharing), Ubuntu
Memory: 748597080 bytes (713 MB) / 1174405120 bytes (1120 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 8 total; -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
Player Count: 1 / 8; [vh['Asadefa'/57, l='Ultra Survive', x=1706.81, y=62.07, z=-132.13]]
Data Packs: vanilla
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.