Why am I getting errors in product.thumbnails.php? [closed]

I’m using the Flatsome theme and getting 404s in the redirection plugin with the error being included at the end of the url, I have contacted the developer, no response just yet and I’m worried this could be damaging my SEO.

Notice: Undefined variable: src in /.../wp-content/themes/flatsome/woocommerce/single-product/product-thumbnails.php/ on line 48

product-thumbnails.php

    <?php
/**
 * Single Product Thumbnails
 *
 * @author      WooThemes
 * @package     WooCommerce/Templates
 * @version     2.6.3
 */

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

global $post, $product, $woocommerce;

$attachment_ids = $product->get_gallery_attachment_ids();

if ( $attachment_ids ) {
    $loop       = 0;
    $columns    = apply_filters( 'woocommerce_product_thumbnails_columns', 4 );

    $arrows="";
    $thumb_count = count($attachment_ids)+1;

    if($thumb_count <= 5){
        $arrows="slider-no-arrows";
    }

    ?>
    <ul class="product-thumbnails <?php echo $arrows; ?> thumbnails js-flickity slider-nav-small"
        data-flickity-options="{ 
                "cellAlign": "left",
                "wrapAround": false,
                "autoPlay": false,
                "prevNextButtons":true,
                "asNavFor": ".product-gallery-slider",
                "percentPosition": true,
                "imagesLoaded": true,
                "pageDots": false,
                "selectedAttraction" : 0.1,
                "friction": 0.6,
                "rightToLeft": false,
                "contain": true
            }"
        ><?php
        $image_link  = wp_get_attachment_url( get_post_thumbnail_id() );
        if ( has_post_thumbnail() ) : ?>
            <li class="is-nav-selected first"><a href="https://wordpress.stackexchange.com/questions/237522/<?php echo $src[0] ?>"><?php echo get_the_post_thumbnail( $post->ID, apply_filters( 'single_product_small_thumbnail_size', 'shop_thumbnail' ) ) ?></a></li>
        <?php endif;

        foreach ( $attachment_ids as $attachment_id ) {

            $classes = array( 'zoom' );

            $image_link = wp_get_attachment_url( $attachment_id );

            if ( ! $image_link )
                continue;

            $image_title    = esc_attr( get_the_title( $attachment_id ) );
            $image_caption  = esc_attr( get_post_field( 'post_excerpt', $attachment_id ) );

            $image       = wp_get_attachment_image( $attachment_id, apply_filters( 'single_product_small_thumbnail_size', 'shop_thumbnail' ), 0, $attr = array(
                'title' => $image_title,
                'alt'   => $image_title
                ) );

            $image_class = esc_attr( implode( ' ', $classes ) );

            echo apply_filters( 'woocommerce_single_product_image_thumbnail_html', sprintf( '<li><a  href="%s" class="%s" title="%s" data-rel="prettyPhoto[product-gallery]">%s</a></li>', $image_link, $image_class, $image_caption, $image ), $attachment_id, $post->ID, $image_class );

            $loop++;
        }
    ?></ul>
    <?php
} ?>

I commented out but errors are still coming through.