Issue #2328629 by Berdir: Fixed Comment::hasParentComment() tries to load comment with ID 0.

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

@@ -324,8 +324,7 @@ public static function bundleFieldDefinitions(EntityTypeInterface $entity_type,
    * {@inheritdoc}
    */
   public function hasParentComment() {
-    $parent = $this->get('pid')->entity;
-    return !empty($parent);
+    return (bool) $this->get('pid')->target_id;
   }
 
   /**