I can confirm that that is a bug in all of the Entrance Doors ... they give an error if there are zero verticals. I'll report it. A further bug in the two french entrance doors is the limited panel choice. Custom belongs there among others.
As a substitute, you can perhaps use the D2 door under Wood Internal? It lets you specify 0 vertical.
Cheers,
Karl
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB
One of the forum moderators