Multilingual Polylang sitemaps for "XML Sitemap & Google News" plugin

polylang-multilingual-sitemap.php

<?php

/**
 * Plugin Name: Multilingual Polylang sitemaps for "XML Sitemap & Google News" plugin
 * Description: For https://wordpress.org/plugins/xml-sitemap-feed/
 * Version:     1.0
 */
add_action('xmlsf_tags_after', function () { // xmlsf_tags_after
  //Bail early.
  if (!function_exists('pll_languages_list')) {
    return null;
  }

  $languages = pll_languages_list(['fields' => '',]); // Returns all fields

  /* @var $language PLL_Language */
  foreach ($languages as $language) {
    $id              = get_the_ID();
    $translated_post = pll_get_post($id, $language->slug);

    $hreflang = $language->slug;
    //Special case for EN
    if (in_array($language->slug, ['eng'])) {
      $hreflang = $language->w3c;
    }

    if ($translated_post) {
?>
      <xhtml:link rel="alternate" hreflang="<?php echo $hreflang; ?>" href="<?php echo get_the_permalink(pll_get_post($id, $language->slug)); ?>" />
<?php
    }
  }
});

add_action('xmlsf_urlset', function ($type) {
  if ($type === 'post_type') {
    echo 'xmlns:xhtml="http://www.w3.org/1999/xhtml"' . PHP_EOL;
  }
});

//Make en-GB one the one to use for all of en locale
add_filter('pll_rel_hreflang_attributes', function ($hreflangs) {
  if (isset($hreflangs['en-GB'])) {
    $hreflangs['en'] = $hreflangs['en-GB'];
    unset($hreflangs['en-GB']);
  }
  return $hreflangs;
});

@halilnevzat Without seeing the full error message, there is no way to tell.