When PO not saved, no mail can be send. Sending a reminder preview will get traceback. In this commit, we check if the PO is saved before sending the mail. Also clean some useless code in the send_reminder_preview() and fix the issue when no json object is return to the widget because of on mail send. Task 2339431 PR #57961 closes odoo/odoo#59399 X-original-commit: 83f2cac4b8ba101d6a7736a8ff408a3fdb5422fe Signed-off-by: William Henrotin <Whenrow@users.noreply.github.com>