more error checking

backend/src/main.py

@@ -69,7 +69,7 @@ def new_trip(preferences: Preferences,
                             osm_id=0,
                             attractiveness=0,
                             must_do=True,
-                            n_tags = 0)
+                            n_tags=0)
 
     # Generate the landmarks from the start location
     landmarks, landmarks_short = manager.generate_landmarks_list(
@@ -132,6 +132,8 @@ def get_landmark(landmark_uuid: str) -> Landmark:
     """
     try:
         landmark = cache_client.get(f"landmark_{landmark_uuid}")
+        if not isinstance(landmark, Landmark) :
+            raise ValueError(f"Object {landmark} is not of type Landmark")
         return landmark
     except KeyError as exc:
         raise HTTPException(status_code=404, detail="Landmark not found") from exc