WordPress debugger sees an undefined constant is the callback function name isn't wrapped in single quotes. Doesn't affect operation of theme as far as I can tell, but WP unit testing suggests addressing these kinds of things.
@@ -22,7 +22,7 @@ if ( post_password_required() ) {
'style' => 'div',
'short_ping' => true,
'avatar_size' => 40,
- 'callback' => bones_comments,
+ 'callback' => 'bones_comments',
'type' => 'all',
'reply_text' => 'Reply',
'page' => '',