code: public function onReplaceInsertTags(string $tag)
      {
          $chunks = explode('::', $tag);
  
          if ('asset' !== $chunks[0]) {
              return false;
          }
  
          $url = $this->packages->getUrl($chunks[1], $chunks[2] ?? null);
  
          // Contao paths are relative to the <base> tag, so remove leading slashes
          return ltrim($url, '/');
      }
docs: Replaces the "asset" insert tag.
  
  @return string|false