UI: top_menu: Convert icon_url to empty str if it is None

Signed-off-by: Alexander Piskun <bigcat88@icloud.com>

Author: bigcat88

nc_py_api/ex_app/ui/top_menu.py

@@ -33,7 +33,7 @@ def display_name(self) -> str:
     @property
     def icon_url(self) -> str:
         """Relative to the ExApp url with icon or empty value to use the default one icon."""
-        return self._raw_data["icon_url"]
+        return self._raw_data["icon_url"] if self._raw_data["icon_url"] else ""
 
     @property
     def admin_required(self) -> bool: