How not to code WP shortcodes

bcwpsc.php

<?php

$output = '';

if ( $related_posts->have_posts() ){
  $out .=  '<h3> Related Posts</h3>';
  $out .= '<ul>';
  while ( $related_posts->have_posts() ){
    $related_posts->the_post();
    $out .= '<li><a href="'.the_permalink().'">'.get_the_title().'</a></li>';
  }
 $out .= '</ul>';
}