Fatal error: Uncaught Error: Class "WP_Widget" not found in /var/www/andovercg/staging/wp-content/plugins/smart-slider-3/Nextend/SmartSlider3/Platform/WordPress/Widget/WidgetSmartSlider3.php:13 Stack trace: #0 {main} thrown in /var/www/andovercg/staging/wp-content/plugins/smart-slider-3/Nextend/SmartSlider3/Platform/WordPress/Widget/WidgetSmartSlider3.php on line 13