foreach() invalid argument error for get_posts

Warning: Invalid argument supplied for foreach() in /home/rem/public_html/wp-includes/query.php on line 1401</p>
<p>Warning: Invalid argument supplied for foreach() in /home/rem/public_html/wp-includes/query.php on line 1401</p>
<p>Warning: Invalid argument supplied for foreach() in /home/rem/public_html/wp-includes/query.php on line 1401</p>
<p>Warning: array_merge() [function.array-merge]: Argument #2 is not an array in /home/rem/public_html/wp-includes/query.php on line 1791

the errors above are caused by a plugin that i wrote to create a sitemap. i develop my plugins on a wordpress mu 2.7.1 install. i recently installed this plugin on a site i am currently developing, and received the above errors.

below are the get_posts queries in the plugin that return the first 3 errors.

$excludes = get_posts('post_type=any&numberposts=-1&meta_key=_ezsitemap_exclude&meta_value=1');
$excludes = get_posts('post_type=any&numberposts=-1&meta_key=_ezsitemap_link&meta_value=1');
$ezsitemap['queries']['pages'] = get_pages('orderby=title&order=asc&exclude='.$ezsitemap['filters']['pages']['hide']);

$excludes is used in two places separated by several lines of coding (working with the results of the queries).

on the wordpress mu site where i develop my plugins, i receive no errors. i also installed the plugin on a wordpress 2.7.1 site, and received no errors.

is there something i am missing? why does this error occur?

any help would be greatly appreciated…