loadBySubscriberEmail() error registering customer account via checkout

[vanmelick]

Magento 2.4.7-p1
mailchimp/mc-magento2 103.4.62

In the checkout, when a guest customer indicates he wants to create an account, he is not redirected to the payment service provider page. The order is created in Magento, but the customer is NOT created.

Error message in logs:
main.CRITICAL: TypeError: Magento\Newsletter\Model\Subscriber\Interceptor::loadBySubscriberEmail(): Argument #2 ($websiteId) must be of type int, null given, called in /magento-root-folder/vendor/mailchimp/mc-magento2/Observer/Customer/SaveBefore.php on line 72 and defined in /magento-root-folder/generated/code/Magento/Newsletter/Model/Subscriber/Interceptor.php:20

We applied this patch to fix it:

--- Observer/Customer/SaveBefore.php	2024-09-09 12:12:12.551523556 +0000
+++ Observer/Customer/SaveBefore.php	2024-09-09 12:14:27.428282120 +0000
@@ -26,6 +26,10 @@
      */
     private $syncHelper;
     /**
+     * @var \Magento\Store\Model\StoreManagerInterface
+     */
+    private $_storeManager;
+    /**
      * @var \Magento\Newsletter\Model\SubscriberFactory
      */
     protected $subscriberFactory;
@@ -38,11 +42,13 @@
     public function __construct(
         \Ebizmarts\MailChimp\Helper\Data $helper,
         SyncHelper $syncHelper,
-        \Magento\Newsletter\Model\SubscriberFactory $subscriberFactory
+        \Magento\Newsletter\Model\SubscriberFactory $subscriberFactory,
+        \Magento\Store\Model\StoreManagerInterface $storeManager
     ) {
         $this->_helper              = $helper;
         $this->syncHelper           = $syncHelper;
         $this->subscriberFactory    = $subscriberFactory;
+        $this->_storeManager = $storeManager;
     }
 
     public function execute(\Magento\Framework\Event\Observer $observer)
@@ -52,7 +58,8 @@
          */
         $customer = $observer->getCustomer();
         $storeId  = $customer->getStoreId();
-        $websiteId = $customer->getWebsiteId();
+        $websiteId = $this->_storeManager->getStore()->getWebsiteId();
+
         if ($this->_helper->getConfigValue(\Ebizmarts\MailChimp\Helper\Data::XML_PATH_ACTIVE)) {
             if ($this->_helper->getConfigValue(\Ebizmarts\MailChimp\Helper\Data::XML_PATH_ECOMMERCE_ACTIVE)) {
                 $mailchimpStoreId = $this->_helper->getConfigValue(

However this reverts (in that file) what was merged via #1823