Small fix from mypy change (#2244)

Signed-off-by: Kristen Armes <[email protected]>

frontend/amundsen_application/api/utils/metadata_utils.py

@@ -105,7 +105,7 @@ def is_table_editable(schema_name: str, table_name: str, cfg: Any = None) -> boo
 def _recursive_set_type_metadata_is_editable(type_metadata: Optional[TypeMetadata], is_editable: bool) -> None:
     if type_metadata is not None:
         type_metadata['is_editable'] = is_editable
-        for tm in getattr(type_metadata, 'children'):
+        for tm in getattr(type_metadata, 'children', []):
             _recursive_set_type_metadata_is_editable(tm, is_editable)