Chapter-26 BSP Interiors: Entities spawning in walls

I was testing what I had of the BSP Interiors chapter (up to right before resetting the build_random_map function to build a random map with all three builders), and I found several entities (items and foes) sometimes spawning in the walls. I double checked my potential errors with a recent clone of the repo and compiling the code for this chapter, I found that the same thing was happening: items and foes in walls.

After some investigation, I believe it may be something about the southern and eastern walls of each new room not being calculated correctly and the spawner thinking that they are valid places to place entities, as it seems that the walls they are spawning in are the southern and eastern ones of the rooms they are supposed to spawn in.

These items are unobtainable as the tiles with walls are still counted as walls and not traverse-able. However foes that spawn in walls are still able to move out of walls if their pathing takes them to a tile that is a traverse-able tile.

Here is an example of what I find, with the cloned-repo code.

Another example: