Issue #2853509 by alexpott: Don't render status messages if there are no messages

core/lib/Drupal/Core/Render/Element/StatusMessages.php

@@ -73,11 +73,14 @@ class StatusMessages extends RenderElement {
    * @see drupal_get_messages()
    */
   public static function renderMessages($type) {
+    $render = [];
+    $messages = drupal_get_messages($type);
+    if ($messages) {
       // Render the messages.
-    return [
+      $render = [
         '#theme' => 'status_messages',
         // @todo Improve when https://www.drupal.org/node/2278383 lands.
-      '#message_list' => drupal_get_messages($type),
+        '#message_list' => $messages,
         '#status_headings' => [
           'status' => t('Status message'),
           'error' => t('Error message'),
@@ -85,5 +88,7 @@ class StatusMessages extends RenderElement {
         ],
       ];
     }
+    return $render;
+  }
 
 }