When looking at the new update light packet, I've noticed that the masks for light nibble arrays that are all empty (the inner array is null) are written incorrectly. Both the sky light and the block light ones write to the same mask (this.e), while there is a separate mask that goes unused (this.f). This doesn't apply to the constructor that takes some existing masks to decide which sections to update, only the one that just takes the data.

I'm not sure if this manifests itself ingame in any way; the only way I know of seeing this is by looking at the packet code itself. As of 18w44a, the two writes to this.e are on lines 38 and 46 of the actual code, and the packet itself is obfuscated as kz.