PHP:
Fatal error: Uncaught Error: Class "WP_Customize_Panel" not found in /www/habi.gna.ch/doc/wp-includes/customize/class-wp-customize-themes-panel.php:17
Stack trace:
#0 {main}
thrown in /www/habi.gna.ch/doc/wp-includes/customize/class-wp-customize-themes-panel.php on line 17