Do not raise a ValueError when reading the "sale_price_uom" field for products that are not saleable
When RPC products and using the read() function with the fields "salable" and "sale_price_uom", if the product is not saleable, a ValueError is raised, aborting the query.
If the product is not saleable, the "sale_uom" field is not required. Therefore, it would be more appropriate for the "sale_price_uom" field to return None (without a value) in this case instead of raising a ValueError.