Stray cats spawn inside non full blocks

The bug
Stray cats can spawn inside non full blocks (like stairs, slabs, chests, etc) and some can suffocate them (like dirt path).

To reproduce:

1. Create a Superflat world in peaceful mode with no villages (Generate structures: disabled)
2. Stay still on the ground and use these commands:

   /tick freeze

   /fill ~50 ~-1 ~50 ~-50 ~-1 ~-50 minecraft:oak_slab[type=top]

   /fill ~2 ~-1 ~2 ~-2 ~-2 ~3 air

   /fill ~2 ~-2 ~2 ~-2 ~-2 ~2 white_bed[part=foot,facing=south]

   /fill ~2 ~-2 ~3 ~-2 ~-2 ~3 white_bed[part=head,facing=south]

   /summon villager ~ ~ ~2 {Passengers:[{id:"minecraft:villager",Passengers:[{id:"minecraft:villager",Passengers:[{id:"minecraft:villager",Passengers:[{id:"minecraft:villager"}]}]}]}]}

   /execute as @e[type=minecraft:villager] run ride @s dismount

   /setblock ~ ~-2 ~ repeating_command_block{powered:1b,Command:"/execute at @e[type=minecraft:cat] run setblock ~ ~1 ~ minecraft:diamond_block"}

   /setblock ~ ~-1 ~ minecraft:stone_pressure_plate

   /tick unfreeze

3. Wait for a message in chat about a block begin changed.
   • If the message appears, look for a diamond block around you and see if under it there is a cat trapped inside a slab.

What I expected to happen was...:
A cat spawning above the slab or not spawning at all.

What actually happened was...:
A cat spawned inside the slab.