We just found that when users were searching for a page on one of our sites that the search results would break when we were using
$Content.Summary(30) in the Page_results.ss template. We were getting this error:
Fatal error: Call to a member function appendChild() on a non-object in /xx/framework/parsers/ShortcodeParser.php on line 124
We're pretty sure this was being caused by at least one correctly formed [embed] shortcode in the content of the results returned.