add invisible render

app.py

@@ -136,6 +136,7 @@ def generate_static_map(geojson_data, bounds=None):
         #log marker
         logging.info(f"Adding invisible marker to {center_lat, center_lng}")
         m.add_marker(CircleMarker((center_lat, center_lng), '#FFFFFF', 0))  # White marker with size 0
+        return m.render()
 
     # Process each feature in the GeoJSON
     for feature in geojson_data["features"]: