Issue #3480035 by mlncn: After upgrading to Mailchimp 2.2.5, failure to get...

Issue #3480035 by mlncn: After upgrading to Mailchimp 2.2.5, failure to get lists results in a fatal error on login

Closes #3480035

mailchimp.module

@@ -111,11 +111,12 @@ function mailchimp_get_list($list_id) {
  */
 function mailchimp_get_lists(array $list_ids = [], $reset = FALSE) {
   $collection = \Drupal::keyValue('mailchimp_lists');
-  $lists = $reset ? NULL : $collection->get('lists');
+  /** @var array<string, mixed> */
+  $lists = $reset ? [] : $collection->get('lists');
 
   // If we have no stored lists, or we are forcing a refresh, get them from
   // Mailchimp.
-  if (empty($lists)) {
+  if ($lists === []) {
     try {
       /** @var \Mailchimp\MailchimpLists $mcapi */
       $mcapi = mailchimp_get_api_object('MailchimpLists');
@@ -161,7+162,7 @@
       }
     }
     catch (\Exception $e) {
       \Drupal::logger('mailchimp')->error('An error occurred requesting list information from Mailchimp. "{message}"', [
         'message' => $e->getMessage(),
       ]);
     }