Well, either set the field “web_address” to “required” or check for existence of the field first before creating the paragraph with the link.
<?php if (get_field('web_address')) { ?>
// your code
<?php } ?>
And I don’t think the link is to the page URL when not filled out in the backend, it’s probably just empty. Try this:
echo get_field('web_address')
And you should get nothing for an empty field.
