pear/pear-core — comment on commit 98328ed8974b15d9006c6c258d93a0f1b5c53cde
File:  line 0
By CloCkWeRX:

So, as I understand it this isn't so much about the warning being emitted, as trying to autoload $data when it's a string.
http://www.roojs.com/blog.php/View/242/.html goes into the details.

It's good if it's fixed in 5.3.9+, but the is_object check doesn't hurt anything afaict, and fixes this for 5.3.7/5.3.8.