Issue #3400501: Moving the 'actions' form element of a signup form into a...

Issue #3400501: Moving the 'actions' form element of a signup form into a wrapper element breaks ajax functionality

Closes #3400501

modules/mailchimp_signup/src/Form/MailchimpSignupPageForm.php

@@ -408,10 +408,11 @@ class MailchimpSignupPageForm extends FormBase {
    *   A ajax response.
    */
   public function ajaxSubmit(array $form, FormStateInterface $form_state) {
+    $triggering_element = $form_state->getTriggeringElement();
     $response = new AjaxResponse();
-    $response_wrapper_id = '#' . $form['actions']['submit']['#ajax']['response_wrapper'];
+    $response_wrapper_id = '#' . $triggering_element['#ajax']['response_wrapper'];
 
-    // Simply return any status messages as a content the the response wrapper.
+    // Simply return any status messages as a content the response wrapper.
     $status_messages = ['#type' => 'status_messages'];
     $content = \Drupal::service('renderer')->renderRoot($status_messages);
     $response->addCommand(new HtmlCommand($response_wrapper_id, $content));