Issue #3162578 by JPHuxley: Notice due to missing submit button

submit_and_continue.module

@@ -24,7 +24,8 @@ function submit_and_continue_form_alter(&$form, $form_state, $form_id) {
   }
 
   foreach ($submit_and_continue_targets as $target_form) {
-    if (\Drupal::routeMatch()->getRouteName() == $target_form['route']) {
+    if (\Drupal::routeMatch()
+        ->getRouteName() == $target_form['route'] && isset($form['actions']['submit']['#submit'])) {
       $form['actions']['submit_and_continue'] = [
         '#type' => 'submit',
         '#submit' => array_merge($form['actions']['submit']['#submit'], ['submit_and_continue_submit']),