Fix: Fix potential NPE in check

CityDoctorParent/CityDoctorValidation/src/main/java/de/hft/stuttgart/citydoctor2/checks/topology/MisalignedUtilityConnectionCheck.java

@@ -281,8 +281,7 @@ public class MisalignedUtilityConnectionCheck extends Check {
         // Calculate intersection plane
         if (!intersections.isEmpty()) {
             List<Vector3d> intersectPoints = intersections.stream()
-                    .flatMap(isect -> isect.getLines().stream())
-                    .flatMap(segment -> Stream.of(segment.getPointA(), segment.getPointB()))
+                    .flatMap(this::getIntersectionPoints)
                     .toList();
 
             if (!intersectPoints.isEmpty()) {
@@ -299,6 +298,17 @@ public class MisalignedUtilityConnectionCheck extends Check {
         return OrthogonalRegressionPlane.calculateOrthogonalRegressionPlane(sPairVerts);
     }
 
+    private Stream<Vector3d> getIntersectionPoints(PolygonIntersection isect) {
+        if (isect.getLines() != null) {
+            return isect.getLines().stream().flatMap(segment -> Stream.of(segment.getPointA(), segment.getPointB()));
+        }
+        if (isect.getT1() != null && isect.getT2() != null) {
+            return Stream.of(isect.getT1().getP1(), isect.getT1().getP2(), isect.getT1().getP3(),
+                    isect.getT2().getP1(), isect.getT2().getP2(), isect.getT2().getP3());
+        }
+        return Stream.empty();
+    }
+
     private boolean isPlanarToPlane(List<Vertex> verts, Plane plane, double eps) {
         if (verts.isEmpty()) {
             return true;