Adding product image to WooCommerce Wishlist emails

Hi,

How do we add product images to the WooCommerce Wishlist emails that get sent when something gets in stock? The current email template that I have copied to my child theme looks like this:

<?php
/**
 * Waitlist Mailout email (plain text)
 *
 * @author		Neil Pie
 * @package		WooCommerce_Waitlist/Templates/Emails/Plain
 * @version		1.2
 */

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

do_action('woocommerce_email_header', $email_heading);
?>

<p><?php echo _x( "Hi There,", 'Email salutation', 'woocommerce-waitlist' ); ?></p>

<p><?php
echo sprintf( __( '%1$s is now back in stock at %2$s.', 'woocommerce-waitlist' ), $product_title, get_bloginfo( 'name' ) ) . " ";
echo __('You have been sent this email because your email address was registered on a waitlist for this product.', 'woocommerce-waitlist' ), $product_image;
?></p>
<p><?php echo sprintf( __( 'If you would like to purchase %1$s please visit the following link: <a href="%2$s">%3$s</a>', 'woocommerce-waitlist' ), $product_title, $product_link, $product_link  );
 ?></p>
 <?php
 if ( WooCommerce_Waitlist_Plugin::persistent_waitlists_are_disabled() )
	echo '<p>' , __('You have now been removed from the waitlist for this product.', 'woocommerce-waitlist' ) , '</p>';
	do_action('woocommerce_email_footer'); ?>

Does anyone have a clue how to add a product photo to this? I tried using below code with no success:

<div style="margin:15px auto;text-align:center">
	<div class="product_image"><?php echo $product->get_image( 'shop_catalog' ); ?></div>
	<div class="product_title"><a href="<?php echo esc_url( add_query_arg( 'product_alert_sid', $session_id, $product->get_permalink() ) ); ?>"><?php echo $product->get_title(); ?></a></div>
	<div class="product_price"><?php echo $product->get_price_html(); ?></div>
</div>