It should not be possible to send a signature form where all mandatory questions have not been completed

When a form is sent for signing, it can be sent even if mandatory questions are not filled in. Afterwards, when we want to close the form, we can't close it because the questions haven't been filled in, but the form has still been sent.

Either it must be possible to override this when the form is sent for signing, or it must actually be possible to fill in all mandatory questions before it is sent.