implode() [function.implode] Invalid arguments passed on line 8

I have a problem with my loop-index.php file. I install a new version of theme and i get this message: Warning: implode() [function.implode]: Invalid arguments passed in /home/arhireab/public_html/clicktech/wp-content/themes/mytheme/loop-index.php on line 8

Click here to see the loop-index.php file
Also my featured image don’t apear anymore on posts

<?php
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1; // gets current page number
global $query_string; // required

/* Exclude categories from Recent Posts */
if (option::get('recent_part_exclude') != 'off') {
	if (count(option::get('recent_part_exclude'))){
		$exclude_cats = implode(",-",option::get('recent_part_exclude'));
		$exclude_cats = '-' . $exclude_cats;
		$args['cat'] = $exclude_cats;
	}
}