loading/creating maps after several times causes `java.lang.IllegalArgumentException: World unloaded`.

I only try to load a map via:

Bukkit.getServer().createWorld(new WorldCreator(mapName));

followed by a teleportation to this newly loaded world.

The map gets saved properly:

ThreadedAnvilChunkStorage (testMap): All chunks are saved

I repeat this procedure, by loading and unloading this map again, 2 times, and it throws this exception:

Stacktrace:

 java.lang.IllegalArgumentException: World unloaded
   at com.google.common.base.Preconditions.checkArgument(Preconditions.java:122)
   at org.bukkit.Location.getWorld(Location.java:112)
   at org.bukkit.Location.serialize(Location.java:1096)
   at dev.dementisimus.mapcreator.creator.AbstractCreator.lambda$load$8(AbstractCreator.java:235)
   at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
   at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
   at java.base/java.lang.Thread.run(Thread.java:834)

After some more testing, it is clear now, that this bug only affects one world, e.g: if I load world MyWorld 2 times, this Exception gets thrown, and if I load another map after this Exception has been thrown, there's again a counter of 2, till this Exception'll be thrown again.

I've already tried it with a cooldown (10sec) after loading this map in, but this does not solve this.