Exceptions after sending player to another instance

[bbSnavy]

There are two instances on the server. Players are sent to the other one whenever they start sneaking.
This would fail with all blocks becoming invisible on the new instance and many exceptions

java.lang.NullPointerException: Unloaded chunk at 6785,66,6862
	at net.minestom.server.instance.Instance.getBlock(Instance.java:601)
	at net.minestom.server.instance.block.Block$Getter.getBlock(Block.java:218)
	at net.minestom.server.collision.BlockCollision.cachedPhysics(BlockCollision.java:79)
	at net.minestom.server.collision.BlockCollision.handlePhysics(BlockCollision.java:35)
	at net.minestom.server.collision.CollisionUtils.handlePhysics(CollisionUtils.java:122)
	at net.minestom.server.collision.PhysicsUtils.simulateMovement(PhysicsUtils.java:35)
	at net.minestom.server.entity.Entity.movementTick(Entity.java:595)
	at net.minestom.server.entity.Entity.tick(Entity.java:566)
	at net.minestom.server.thread.TickThread.tick(TickThread.java:74)
	at net.minestom.server.thread.TickThread.run(TickThread.java:49)

[bbSnavy]

There is no error when sneaking while jumping or in the air

[bbSnavy]

Turns out it was a cache issue, fixed with #2086