Display Discount/Offer percentage in WooCommerce

sale-flash.php

<?php
/**
 * Product loop sale flash
 *
 * @author 	Vivek R @ WPSTuffs.com
 * @package 	WooCommerce/Templates
 * @version     1.6.4
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

global $post, $product;
?>
<?php if ($product->is_on_sale() && $product->product_type == 'variable') : ?>

	<div class="bubble">
            <div class="inside">
              <div class="inside-text">
              	<?php 
			$available_variations = $product->get_available_variations();								
			$maximumper = 0;
			for ($i = 0; $i < count($available_variations); ++$i) {
				$variation_id=$available_variations[$i]['variation_id'];
				$variable_product1= new WC_Product_Variation( $variation_id );
				$regular_price = $variable_product1 ->regular_price;
				$sales_price = $variable_product1 ->sale_price;
				$percentage= round((( ( $regular_price - $sales_price ) / $regular_price ) * 100),1) ;
					if ($percentage > $maximumper) {
						$maximumper = $percentage;
					}
				}
				echo $price . sprintf( __('%s', 'woocommerce' ), $maximumper . '%' ); ?></div>
            </div>
     </div><!-- end callout -->

<?php elseif($product->is_on_sale() && $product->product_type == 'simple') : ?>
	
	<div class="bubble">
	           <div class="inside">
	             <div class="inside-text">
	             	<?php 
				$percentage = round( ( ( $product->regular_price - $product->sale_price ) / $product->regular_price ) * 100 );
				echo $price . sprintf( __('%s', 'woocommerce' ), $percentage . '%' ); ?></div>
	           </div>
	    </div><!-- end bubble -->

<?php endif; ?>

Hi,

This have issue when one variation of product have sale price and one variation don't have sale price

• Variation 1: Regular price: $18 - Sale price: $16
• Variation2: Regular price: $20

The error message is
A non-numeric value encountered in woocommerce/templates/single-product/sale-flash.php on 27