Warning: Invalid argument supplied for foreach

Hi. I tried to fix it by myself but after 5 hours on this I understood that I can’t…

I got error on site footer:
Warning: Invalid argument supplied for foreach() in /footer.php on line 91
On home page every thing allright. It appears on woocommerce product…
Please help to fix it…
Here’s lines from footer.php
Line 91 starts: foreach ($terms as $term) {

</div><?php
		$category = get_the_category();
		if(function_exists( 'is_woocommerce' ) && is_woocommerce() ){
		$terms = get_the_terms( $post->ID, 'product_cat' );
		$category='';
		foreach ($terms as $term) {
			$category.= $term->name.', ';
			//break;
			if($category==""){
				$category="";
			}
		}
		}