I left that out intentionally. So that when you put in walls it could 'tie' in given that it was more in the centre of the room as opposed to an edge wall. So no, it wasn't 'missed' it was part of the design. If you didn't want to put a 'wall' in then you could place a regular stone wall post to 'fill in' the gap.
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In my case I ended up putting in a stone arch piece highlighted yellow. My design was always intended to allow people to customize the internal walls to their liking instead of forcing people to whatever configuration suited me. I don't understand why anyone would design with internal walls unless they are using a tile that cannot be paired with grey stone. If you want flexibility then making the outside look the business while allowing players to do their own insides in my view the way to go.
The ODD gap on sth and east walls is no big deal if your deco is up to scratch, it disappears into the background, as for not being able to deco without circ, well all the external walls are solid so it is just the ones you add yourself that aren't and sheesh, pick it up, do your deco and put it back down. If you have to hide stuff behind walls as there isn't room to deco and see the items without them being placed behind walls then the rooms are too small to start with.
So no, not Oops at all
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