For some reason, this script works perfectly in a test environment. Use case: create a finish floor per room that takes into account any door openings, and extends the boundary into that threshold area. See image and attached script.
CreateFloors_fromRooms.dyn (176.4 KB)
It fails on every attempt within the project intended for use.
Could it be related to worksharing, or links? Even a simple rectangular room it fails to obtain the boundary.
What happens if you run the script not in the Player, but straight from Dynamo in the problem project? Then you can track the results of the nodes and find out if some output is not in the expected format.
I’ve discovered that since the project is using Shared Coordinates, the Level Plane for intersection of the solid boolean of the room and door openings was missing the target. That will teach me to put an entire graph behind a scopeIf error trap. Fixed it. 
@seandburke I tried uit your script and it works great! Only I don’t want the floor to stop in the middle of the dooropening, but on either side of the wall, depending on the door orientation… like this:
Would it be possible you think?
Somehow I only need to select/get the doors going out of the room… (like door on the left)
