That quote is from a user comment. I suspect they wanted to write an example but 
not worry about whether, for example, $xslDoc is an object. So if ($foo) { $foo-
>bar(); } vs simply $foo->bar(); 

However, it's a reasonable request. We should add an example that utilizes 
ext/libxml for error handling here. See:

http://php.net/manual/en/book.libxml.php

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.