Fatal error: Uncaught Error: Call to a member function has_book() on null in /www/nyupressorg_620/public/wp-content/themes/university_press_theme/functions/author-page-shortcode.php:19 Stack trace: #0 /www/nyupressorg_620/public/wp-includes/shortcodes.php(325): upt_author_page('', '', 'authors-details') #1 [internal function]: do_shortcode_tag(Array) #2 /www/nyupressorg_620/public/wp-includes/shortcodes.php(199): preg_replace_callback('/\\[(\\[?)(author...', 'do_shortcode_ta...', '\n[authors-detai...') #3 /www/nyupressorg_620/public/wp-includes/class-wp-hook.php(286): do_shortcode('\n[authors-detai...') #4 /www/nyupressorg_620/public/wp-includes/plugin.php(208): WP_Hook->apply_filters('\n[authors-detai...', Array) #5 /www/nyupressorg_620/public/wp-includes/post-template.php(247): apply_filters('the_content', '<!-- wp:paragra...') #6 /www/nyupressorg_620/public/wp-content/themes/university_press_theme/templates/template-full-width.php(10): the_content() #7 /www/nyupressorg_620/public/wp-includes/template-loader.php(78): in in /www/nyupressorg_620/public/wp-content/themes/university_press_theme/functions/author-page-shortcode.php on line 19