With updated PHP version WP Code Highlight – gives preg_replace error. Do the following. Remove the “e” from /ise

 return preg_replace_callback("/<pre(.*?)>(.*?)<\/pre>/is",
 function($m){
 return "<pre class='wp-code-highlight prettyprint$line_numbers'>".wch_stripslashes($m[2])."</pre>";
 }, $content);