Issue #2207219 by larowlan: Fatal: Call to a member function isSubclassOf() on...

Issue #2207219 by larowlan: Fatal: Call to a member function isSubclassOf() on a non-object in CommentManager.

core/modules/comment/lib/Drupal/comment/CommentViewBuilder.php

@@ -228,7 +228,7 @@ protected static function buildLinks(CommentInterface $entity, EntityInterface $
       if ($entity->access('create')) {
         $links['comment-reply'] = array(
           'title' => t('Reply'),
-          'href' => "comment/reply/{$entity->getCommentedEntityId()}/{$entity->getCommentedEntityId()}/{$entity->getFieldName()}/{$entity->id()}",
+          'href' => "comment/reply/{$entity->getCommentedEntityTypeId()}/{$entity->getCommentedEntityId()}/{$entity->getFieldName()}/{$entity->id()}",
           'html' => TRUE,
         );
       }

core/modules/forum/lib/Drupal/forum/Tests/ForumTest.php

@@ -460,6 +460,11 @@ function testForumWithNewPost() {
     $this->drupalPostForm('node/' . $node->id(), $edit, t('Save'));
     $this->assertResponse(200);
 
+    // Test replying to a comment.
+    $this->clickLink('Reply');
+    $this->assertResponse(200);
+    $this->assertFieldByName('comment_body[0][value]');
+
     // Login as the first user.
     $this->drupalLogin($this->admin_user);
     // Check that forum renders properly.