There's a bug when using export('atom') method on a Zend\Feed\Writer\Feed object. This feed is generated by a new Feed() and contain Entry objects added by addEntry() method.

Here is the stack trace: http://paste.keuse.fr/view/22819988.html

The problem appears when Feed generated contain some chars.

First, if an entry contain an ampersand (which is not used for special chars, for example if it's used in a company name), it seems that $dom->loadXml() fails and $dom->documentElement is null.

Moreover, some special chars generated by "&" (like "&"nbsp; or "&"raquo; ) can't be parsed by loadXml() and raise the same error. But some over special chars works (like "&"amp; )... This issue can be solved if we use number based chars (like "&"#160; instead of "&"nbsp; ).

Can you fix it, please? :)