Update visualizer_app.py

visualizer_app.py

@@ -63,7 +63,9 @@ with app.setup:
         if creds_var_name in globals():
             creds_dict = globals()[creds_var_name]
             if isinstance(creds_dict, dict) and key in creds_dict:
-                return creds_dict[key]
+                # Return empty string if the value is None
+                value = creds_dict[key]
+                return "" if value is None else value
         return default
 
 @app.cell