[ArchCurtainWall] Regression Curve Support

Fix https://github.com/FreeCAD/FreeCAD/issues/23945

"Arch_CurtainWall results in an error when trying to create it based on a sketch consisting of spline or arc."

This fixes the regression introduced in -
147e97d407 (diff-b4849bbc0941a0f60f25d13c40d4bfeca94171f55bd78a6196362343c3fdcf6fR287)

src/Mod/BIM/ArchCurtainWall.py

@@ -287,7 +287,8 @@ class CurtainWall(ArchComponent.Component):
             # Fix issue in 'Curtain wall vertical/horizontal mullion mix-up'
             # https://github.com/FreeCAD/FreeCAD/issues/21845
             #
-            face_plane = face.findPlane()  # Curve face (surface) seems return no Plane
+            face_plane = face.findPlane()
+
             if face_plane:
                 if -0.001 < face_plane.Axis[2] < 0.001:  # i.e. face is vertical (normal pointing horizon)
                     faceVert = True
@@ -302,6 +303,9 @@ class CurtainWall(ArchComponent.Component):
                         horizsec = obj.HorizontalSections
                 else:
                     faceVert = False
+            else:
+                # Curve extruded face (surface) seems return no Plane - need more robust algorithm
+                faceVert = False
 
             # Guess algorithm if face is not vertical
             if not faceVert: