Sale badge compatible with sober theme

Ensure sale badges work with sober theme.

if (!function_exists('woo_discount_rules_sober_product_ribbons')) {
    function woo_discount_rules_sober_product_ribbons($output, $product){
        if(empty($output['onsale'])){
	    	if ( $product->is_on_sale() ) {
			$output['onsale'] = '<span class="onsale ribbon">Special Sale</span>';
	    	}
        } else {
	    	$product_id = $product->get_id();
	    	if(class_exists('\Wdr\App\Controllers\ManageDiscount')){
	        	$isProductOnSale = Wdr\App\Controllers\ManageDiscount::isProductOnSale($product_id);
	        	if($isProductOnSale){
	           		$output['onsale'] = '<span class="onsale ribbon">Special Sale</span>';
	       		}
            }
        }
    return $output;
   }
}
add_filter('sober_product_ribbons', 'woo_discount_rules_sober_product_ribbons', 100, 2);