Allow Undefined topology representations for IfcStructuralPointConnection #6459

Because apparently it's not invalid IFC.
IfcStructuralPointConnection documentation says that they should have a topology representation with a IfcVertexPoint but it doesn't restict this representation from having Undefined type if it does have a IfcVertexPoint as it's item.

src/bonsai/bonsai/bim/import_ifc.py

@@ -717,9 +717,15 @@ class IfcImporter:
     def create_structural_point_connections(self):
         for product in self.file.by_type("IfcStructuralPointConnection"):
             # TODO: make this based off ifcopenshell. See #1409
-            representation: ifcopenshell.entity_instance = next(
-                rep for rep in product.Representation.Representations if rep.RepresentationType == "Vertex"
-            )
+
+            representation = tool.Structural.get_vertex_representation(product)
+            if not representation:
+                print(
+                    "WARNING. Skipping invalid IfcStructuralPointConnection - "
+                    f"element has no valid representation:\n{product}."
+                )
+                continue
+
             mesh = tool.Loader.create_structural_point_connection_mesh(representation)
             if mesh is None:
                 continue

src/bonsai/bonsai/tool/loader.py

@@ -799,6 +799,7 @@ class Loader(bonsai.core.tool.Loader):
 
         # TODO implement non cartesian point vertices.
         if not point.is_a("IfcCartesianPoint"):
+            print(f"WARNING. Unsupported point type for IfcStructuralPointConnection: {point}.")
             return
 
         ifc_file = tool.Ifc.get()

src/bonsai/bonsai/tool/structural.py

@@ -172,3 +172,42 @@ class Structural(bonsai.core.tool.Structural):
             new = props.structural_analysis_models.add()
             new.ifc_definition_id = ifc_definition_id
             new.name = model["Name"] or "Unnamed"
+
+    @classmethod
+    def get_vertex_representation(
+        cls, product: ifcopenshell.entity_instance
+    ) -> Union[ifcopenshell.entity_instance, None]:
+        """
+        :param product: IfcStructuralPointConnection
+        :return: IfcTopologyRepresentation if it's valid.
+        """
+        vertex_representation, undefined_representation = None, None
+        # At least 1 representation is mandatory in IFC for IfcStructuralPointConnection.
+        for rep in product.Representation.Representations:
+            rep: ifcopenshell.entity_instance
+            rep_type: str = rep.RepresentationType
+            if rep_type == "Vertex":
+                vertex_representation = rep
+                break
+            # It's possible to have 'Undefined' or some other non-predefined type.
+            elif rep_type not in ("Edge", "Path", "Face", "Shell"):
+                undefined_representation = rep
+
+        if not vertex_representation and not undefined_representation:
+            return
+
+        # All other checks in this case are covered by IFC validation.
+        if vertex_representation:
+            items = vertex_representation.Items
+            if len(items) != 1:
+                return None
+            return vertex_representation
+
+        if undefined_representation is None:
+            return
+
+        items = undefined_representation.Items
+        if len(items) != 1 or not all(item.is_a("IfcVertex") for item in items):
+            return None
+
+        return undefined_representation