diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 0182aab..4824a96 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -24,7 +24,7 @@ class ApplicationController < ActionController::Base
   end
 
   def current_user_is_author?(article)
-      @current_user.id == article.user_id
+    @current_user && @current_user.id == article.user_id
   end
 
   def current_user_can_star?(article)
diff --git a/app/views/articles/_comment_form.html.haml b/app/views/articles/_comment_form.html.haml
index ba889da..a21db4c 100644
--- a/app/views/articles/_comment_form.html.haml
+++ b/app/views/articles/_comment_form.html.haml
@@ -22,4 +22,4 @@
       $(this).tab('show');
       preview('article_comment_content', 'preview');
     });
-  });
+  });
\ No newline at end of file
diff --git a/public/images/92f056f5-214a-4c03-b3a0-6cc61ebc116a.jpg b/public/images/92f056f5-214a-4c03-b3a0-6cc61ebc116a.jpg
new file mode 100644
index 0000000..534ed16
Binary files /dev/null and b/public/images/92f056f5-214a-4c03-b3a0-6cc61ebc116a.jpg differ