I figured this out. What fixed it was I needed to use isset in the conditional.
old code:
if (!$_POST['delivery']){
wc_add_notice( sprintf(__('You must accept Additional Shipping Conditions.', 'themename')) ,'error' );
}
if (!$_POST['customer']){
wc_add_notice( sprintf(__('You must accept responsibility for address misplacement.', 'themename')) ,'error' );
}
Correct code using isset:
if (!isset($_POST['delivery'])){
wc_add_notice( sprintf(__('You must accept Additional Shipping Conditions.', 'themename')) ,'error' );
}
if (!isset($_POST['customer'])){
wc_add_notice( sprintf(__('You must accept responsibility for address misplacement.', 'themename')) ,'error' );
}