fix: retrieve issue url only when issue_tracker_type is set

Author: StefanFl

backend/application/core/api/serializers_observation.py

@@ -128,7 +128,7 @@ def get_origin_cloud_resource_url(self, observation: Observation) -> Optional[st
     def get_issue_tracker_issue_url(self, observation: Observation) -> Optional[str]:
         issue_url = None
 
-        if observation.issue_tracker_issue_id:
+        if observation.issue_tracker_issue_id and observation.product.issue_tracker_type:
             issue_tracker = issue_tracker_factory(observation.product, with_communication=False)
             issue_url = issue_tracker.get_frontend_issue_url(observation.product, observation.issue_tracker_issue_id)