WordPress 6.3 to 6.4 now getting JS error in my plugin

I wrote what is a relatively simple plugin that allows users on my woocommerce store to add a free sample to their basket, it’s been working great until wordpress auto updated to 6.5, now when the users clicks to add a sample to the basket they get this error,

Cannot read properties of undefined (reading ‘0’)

with this stacktrace,

Uncaught TypeError: Cannot read properties of undefined (reading '0')
    at document.body.onadded_to_cart (main.js?ver=c4a77335eae7e6132482:1:3147)
    at Object.trigger (jquery.min.js?ver=3.7.1:2:70175)
    at HTMLBodyElement.<anonymous> (jquery.min.js?ver=3.7.1:2:70726)
    at Function.each (jquery.min.js?ver=3.7.1:2:3129)
    at e.<computed>.each (jquery.min.js?ver=3.7.1:2:1594)
    at e.<computed>.trigger (jquery.min.js?ver=3.7.1:2:70701)
    at HTMLButtonElement.<anonymous> (gifts-at-checkout.js?ver=6.5:112:26)
    at HTMLLIElement.dispatch (jquery.min.js?ver=3.7.1:2:40035)
    at v.handle (jquery.min.js?ver=3.7.1:2:38006)

The gifts-at-checkout.js is the javascript my plugin loads in and the line is this,

$(document.body).trigger('added_to_cart', [$thisbutton, data]);

which is one line of this click event.

$( 'li' ).on( 'click', '.single_add_to_cart_button', function(e) {
        e.preventDefault();
        var $thisbutton = $(this),
            $form = $thisbutton.closest('form.cart'),
            id = $thisbutton.val(),
            product_qty = $form.find('input[name=quantity]').val() || 1,
            product_id = id,
            variation_id = $form.find('input[name=variation_id]').val() || 0;

        var data = {
            action: 'woocommerce_ajax_add_to_cart',
            product_id: product_id,
            product_sku: '',
            quantity: product_qty,
            variation_id: variation_id,
        };

        $(document.body).trigger('added_to_cart', [$thisbutton, data]);

        $.ajax({
            type: 'post',
            url: wc_add_to_cart_params.ajax_url,
            data: data,
            beforeSend: function (response) {
                $thisbutton.removeClass('added').addClass('loading');
            },
            complete: function (response) {
                $thisbutton.addClass('added').removeClass('loading');
                $thisbutton.parent().addClass("in-cart");
            },
            success: function (response) {

                if (response.error && response.product_url) {
                    window.location = response.product_url;
                    return;
                } else {
                    $(document.body).trigger('update_checkout', [response.fragments, response.cart_hash, $thisbutton]);
                    selectedSamples.push(product_id);
                    if(selectedSamples.length == parseInt(scriptParams.samples_threshold)) {
                        $('li .single_add_to_cart_button').addClass('isDisabled');
                    }
                }
            },
        });

        return false;
    });

I assume that something in wordpress core in woocommerce core has changed but I cannot for the life of me figure out what, can anyone shed any light on this for me?

Many thanks