Some Entities still spawn with structures in skyvoid_worldgen_empty

[LucySebast]

https://github.com/BPR02/SkyBlock_Collection/wiki/Collection states "The skyvoid_worldgen_empty data pack generates a fully void world in which no blocks or entities will generate."
I however did see gurdians spawn at monuments, chest minecarts at mesa mineshafts and witches & cats at swamp huts.
Allays dont seem to spawn, I searched through multiple mansions and outposts without any and crosschecked with mansions that do have allays on the actual seed, allays would be the only mob that would really make a difference because they dont die instantly, so its really just an annoyance.

I tped to a bunch of structures with an open piechart that usually spawn with entities during initial worldgen but those were the only examples I could find where entities do actually spawn.
(The minecraft:item in the screenshot is just an elder_guardians item drop)

From my testing, the nether is fine and the end also had nothing spawn in end cities.
The dragon does spawn, which is contradictory to the "no blocks or entities will generate." but is probably still the more expeced result, the end fountain also generates ats its original height with initial worldgen, which you could argue shouldnt happen (broken exit portal generation was fixed in 25w09a, so in theory you should be able to remove it without problems), but tbh it doesnt really make a difference as the end is usually inaccessible in this version of the pack either way.

[Ciremya01]

Those are normal behaviour. It's just that when the datapack description says "generate" it's post first world generation (so it's more "replace"). It just remove the blocks when generating chunks.
As for the entities you saw, those are generated with the structure they spawn on (1 witch and cat per witch hut, guardians on ocean monuments, and chest minecarts on mineshaft). Yea it's seems that either the spawn condition for allays is different or that they dye faster than other mobs when falling to the void (we should also see iron golem for pillager outpost).
It's not a problem since when the chunk generate, the structure "spawn" (with blocks and entities), then the datapack remove the blocks, and the entities fall to their death in the void.

For the end yes exit end portal was fixed, but the datapack was originaly created before that, and at this time the dragon and portal were needed not to break the end, we just kept it like that.

[LucySebast]

From my (limited) understanding, structure blocks are used to spawn the mobs that spawn during initial world generation, Though Im not completely sure if that also applies to older structures. In theory it should be possible to stop these entities from spawning by preventing those structure blocks from spawning? Mansions are definitly one of the structures that use them (as seen here), which could be the reason why no allays (or illagers) appeared on my piechart there. Witch Huts, Ocean Monuments and Mineshafts are all older than structure blocks, so this makes sence. If thats the case, the only fix I could think of would be to override how the structure itself spawns, which might be a bit overkill just to avoid some falling entities - but all of that is just from my limited understanding of world generation and might be wrong