Issue #3240171 by andypost, alexpott, larowlan:...

Issue #3240171 by andypost, alexpott, larowlan: \Drupal\comment\Entity\Comment::getSubject() can cause deprecations on PHP 8.1

core/modules/comment/src/Entity/Comment.php

@@ -389,7 +389,7 @@ public function getFieldName() {
    * {@inheritdoc}
    */
   public function getSubject() {
-    return $this->get('subject')->value;
+    return $this->get('subject')->value ?? '';
   }
 
   /**