Check has post next and previous link

<?php
$previous_post = get_adjacent_post(false, '', true);
$next_post = get_adjacent_post(false, '', false);
?>
<ul>
<?php if ($previous_post): // if there are older articles ?>
    <li class="prev">Previous post: <a href="<?php echo make_href_root_relative(get_permalink($previous_post)); ?>"><?php echo get_the_title($previous_post); ?></a></li>
<?php endif; ?>
<?php if ($next_post): // if there are newer articles ?>
    <li class="next">Next post: <a href="<?php echo make_href_root_relative(get_permalink($next_post)); ?>"><?php echo get_the_title($next_post); ?></a></li>
<?php endif; ?>
</ul>