When error is null

After the gateway API changed, every new response started carrying an error key. Declines contain an object there, while the other new responses contain JSON null; older non-decline responses have no error key at all. Find the cases where the gateway explicitly sent no error. What to return: - payment_id — the gateway response ID - order_id — the order ID - status — the status from response Keep in mind: - the error key must be present - its value must be JSON null Sort by payment_id ascending.