Use category image instead custom placeholder on Woocommerce

functions.php

/**
 * Change the placeholder image
 */
add_filter('woocommerce_placeholder_img_src', 'custom_woocommerce_placeholder_img_src');

function custom_woocommerce_placeholder_img_src($src)
{
	global $post;
	$terms = wp_get_post_terms($post->ID, 'product_cat');
	$thumbnail_id = get_woocommerce_term_meta($terms[0]->term_id, 'thumbnail_id', true);
	if (!empty($thumbnail_id)) {
		$image = wp_get_attachment_image_src( $thumbnail_id, 'thumb' );
		$src = $image[0];
	}
	return $src;
}