Fix: Initialize transient fields after deserializing

CityDoctorParent/CityDoctorModel/src/main/java/de/hft/stuttgart/citydoctor2/datastructure/Geometry.java

@@ -349,6 +349,8 @@ public class Geometry extends GmlElement {
     @Serial
     private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
         in.defaultReadObject();
+        edges = new ArrayList<>();
+        edgeMap = new HashMap<>();
         updateVertices();
     }