Previously any random error could occur during an AsyncTask preparing a chunk, and the Level would never know about it and thus never send the chunk.
I don't know how many invisible-chunk bug cases this fixes, but I expect it's quite a lot.
This reverts commit 0081e30a896a730f9598353353f6ee258803850e.
The logic introduced by this commit is correct in MC JAVA 1.9+. Unfortunately, nobody likes 1.9+ for combat.
Some testing in MCPE vanilla made it apparent that this logic isn't correct for MCPE. The old logic is correct for pre-1.9 knockback.
it's possible to walk off a tower while flying without moving vertically, and this code previously wouldn't detect that, leaving a gaping hole in the anti-cheat.
this was an interesting bug.
This was discovered by making a projectile's drag 0, making its gravity a factor of its throw force (such that force / gravity = integer value), and then throwing it directly up. At the apex, an error would occur due to trying to do a ray trace with a zero vector.
This also led me to realize that there's an edge case in the current movement system - if an entity's motion reaches 0, it will stop getting movement updates. This can be undesirable when things such as gravity cause motion to become zero when throwing a projectile directly upwards. This will need to be fixed separately.
I don't care if this matches PC behaviour or not. bugs.mojang.com is full of bug reports about this. Just search for "minecraft spawn protection not working" and you'll see what I mean.
If you want to disable spawn protection, actually disable it. This behaviour is something that most users are not aware of and find astonishing when they discover it.
This behaviour was copied from Minecraft PC, and it's nearly as unexpected there as it is here.
This commit reverses the stupidity done in eb0525e892219508d0c0e4602e835d5ddbacaf45.
fixes#2295
There is still an issue in that the spawn point will not be offset if the chunk is not generated, but this is better than the spawn point being down at y=0. The other issue is a job for another time.
