Turn comic image into "next comic" link

next-comic-link-example.php

<?php
    /**
     * Pull in options
     */
    $group_comics = MangaPress_Bootstrap::get_instance()->get_option('basic', 'group_comics');
    $group_by_parent = MangaPress_Bootstrap::get_instance()->get_option('basic', 'group_by_parent');

    /**
     * @link https://github.com/mangapress/mangapress/blob/master/includes/functions.php#L234
     */
    $next_comic = mangapress_get_adjacent_comic($group_comics, $group_by_parent, 'mangapress_series', '', false);
    $next_comic_link = get_permalink(get_post_field('ID', $next_comic));
?>

<a href="<?php echo esc_url($next_comic_link); ?>"><?php the_post_thumbnail(); ?></a>