[Plugin: Collapsing Categories] PHP Warning foreach() in collapscat.php

Hello,
I like your plugin, just one small problem.
I am getting a PHP warning over and over.
It says :
PHP Warning: Invalid argument supplied for foreach() in /wp-content/plugins/collapsing-categories/collapscat.php on line 103

How can I fix this?

Thank you for the great work!
It is a very useful plugin.

http://wordpress.org/extend/plugins/collapsing-categories/