Advanced Ads — Convert <div> to <aside>

functions.php

<?php

/**
* Changes ad wrapper <div> element to <aside> element
* Does not work with cache-busting containers
*
* @param string $output ad output.
* @param object $ad Advanced_Ads_Ad object.
*
* @return string
*/

add_filter( 'advanced-ads-ad-output', function( $output, $ad ) {

  $type = $ad->type;

  if( $type != 'group' ) {
    $output = preg_replace( '/^( <div )/', '<aside ', $output );
    $output = preg_replace( '/(<\/div>)($|<script>)/', "</aside>\n$2", $output );
  }

  return $output;

}, 10, 2 );

Updated to properly convert the closing tag in case the closing tag is immediately followed by a script.