Error when parsing valid cube models with empty pre-aggregations section

Cube generates models from a table in a database with an empty pre-aggregation section.
When trying to load_from_directory() or to adapter.parse() using the CubeAdapter on a yml file with such an empty pre-aggregation section, sidemantic throws an error as None type cannot be parsed.
As files are generated as such by cube and are valid cube file, this case should be taken into account.