Deprecated: Function get_currentuserinfo is deprecated since version 4.5.0! Use wp_get_current_user() instead. in /var/www/html/wp-includes/functions.php on line 5383
you’re right, it’s a bug. Please download this fix, unzip it, and upload the contained file into the theme folder (/wp-content/themes/Kanso/), replacing the existing file.
Please accept my apologies for this one, and thank you for bring it up! I will include the fix into the upcoming theme update.