Problem when user already subcribed

Hello.
We use the premium version with mailpoet.

If a user chooses to subscribe and then for some reason chooses to subscribe again, no warning comes.
Just a console message (F12) giving an error 500.
The server log says:

[22-Mar-2022 13:13:09 UTC] PHP Fatal error:  Uncaught MailPoet\API\MP\v1\APIException: This subscriber already exists. in /home/xxxxxx/public_html/wp-content/plugins/mailpoet/lib/API/MP/v1/API.php:137
Stack trace:
#0 /home/xxxxxxx/public_html/wp-content/plugins/woocommerce-coupon-box/frontend/frontend.php(251): MailPoet\API\MP\v1\API->addSubscriber(Array, Array)
#1 /home/xxxxx/public_html/wp-includes/class-wp-hook.php(307): VI_WOOCOMMERCE_COUPON_BOX_Frontend_Frontend->wcb_email('')
#2 /home/xxxxx/public_html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array)
#3 /home/xxxxxx/public_html/wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#4 /home/xxxxx/public_html/wp-admin/admin-ajax.php(202): do_action('wp_ajax_nopriv_...')
#5 {main}
  thrown in /home/xxxxxx/public_html/wp-content/plugins/mailpoet/lib/API/MP/v1/API.php on line 137