Lighting Crash

[ghost]

So I was playing minekhan on willard.fun. Then everything went blank. Here is a screenshot:

[Willard21]

Was someone else in the world? I wrapped it in a try-catch to stop it from freezing from that multiplayer lighting bug, but that happens instead, so it's not a great fix lol.

[ghost]

I wasn't in multiplayer.

[Willard21]

Oh. Were you building at the edge of ungenerated chunks or something then? 🤔

[ghost]

I was playing around with slabs and it was nowhere near ungenerated chunks.

[ghost]

There were also some dropped items but they were really far away.

[ghost]

It's prob willard. as herobrine

[ghost]

I just joined a multiplayer world and everything was blank. It looks like the same thing as the screenshot above.

[ghost]

I think I found out how to reproduce this bug but its not quite right. EDIT: I think this is actually another bug.

1. So make a 3x3 square above the ground.
2. Put a upside-down slab on one edge (not the corner)
3. Throw an item in the middle of the square.
4. If the item falls through the square, you did it right
5. Wait
6. Everything goes weird. So if you throw more items, There will be weird things going on.

Screenshot:

[ghost]

Actually if you throw an item at a bunch of upside-down slabs above the ground, it will also happen

[ghost]

There are a lot of errors in the console.

[ghost]

I think you need to change the getlight function. Just make it so if the y is less than 1, return 0.

[Willard21]

Can you send a small world save with reproduction steps? This bug has been around for awhile, but I've only experienced it myself in multiplayer, and only very sporadically, so I haven't been able to debug it to fix it.

[ghost]

I don't know how to reproduce the first bug. For the second bug, You just have to throw an item on an upside-down slab.

[ghost]

I think this fixes the bug:

getLight(x, y, z, blockLight = 0) {
	if(y < 1) return 0 //<= that
	let X = (x >> 4) + this.offsetX
	let Z = (z >> 4) + this.offsetZ
	if (X < 0 || X >= this.lwidth || Z < 0 || Z >= this.lwidth) {
		return this.chunks[x >> 4][z >> 4].getLight(x & 15, y, z & 15, blockLight)
	}
	return this.loaded[X * this.lwidth + Z].getLight(x & 15, y, z & 15, blockLight)
}

Putting this in the console can also fix it:

world.__proto__.getLight = function(t,e,r,n=0){
if(e<1) return 0;
var o=(t>>4)+this.offsetX,i=(r>>4)+this.offsetZ;return(o<0||o>=this.lwidth||i<0||i>=this.lwidth?this.chunks[t>>4][r>>4]:this.loaded[o*this.lwidth+i]).getLight(15&t,e,15&r,n)}

[Blqtent]

Ummm, what?

[Willard21]

Reading over this again, it appears the crash was caused by dropped items outside rendered chunks. As dropped items are gone, this shouldn't be an issue any more. Hopefully.