Fatal error: Uncaught TypeError: array_merge(): Argument #2 must be of type array, null given in /var/www/html/wp-includes/widgets.php:609
Stack trace:
#0 /var/www/html/wp-includes/widgets.php(609): array_merge(Array, NULL)
#1 /var/www/html/wp-includes/class-wp-widget.php(576): _register_widget_update_callback(NULL, Array, NULL, Array)
#2 /var/www/html/wp-includes/class-wp-widget.php(275): WP_Widget->_register_one()
#3 /var/www/html/wp-includes/class-wp-widget-factory.php(103): WP_Widget->_register()
#4 /var/www/html/wp-includes/class-wp-hook.php(324): WP_Widget_Factory->_register_widgets('')
#5 /var/www/html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#6 /var/www/html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#7 /var/www/html/wp-includes/widgets.php(1862): do_action('widgets_init')
#8 /var/www/html/wp-includes/class-wp-hook.php(324): wp_widgets_init('')
#9 /var/www/html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#10 /var/www/html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#11 /var/www/html/wp-settings.php(695): do_action('init')
#12 /var/www/html/wp-config.php(98): require_once('/var/www/html/w...')
#13 /var/www/html/wp-load.php(50): require_once('/var/www/html/w...')
#14 /var/www/html/wp-blog-header.php(13): require_once('/var/www/html/w...')
#15 /var/www/html/index.php(17): require('/var/www/html/w...')
#16 {main}
  thrown in /var/www/html/wp-includes/widgets.php on line 609