Does not work in Customizer’s Widgets

Trying to add in Customizer causes this UI error: https://share.getcloudapp.com/04u20XY9

And causes these PHP notices:

PHP Notice: Undefined index: mp_featuredimg_1 in /wp-includes/class-wp-customize-widgets.php on line 577
PHP Stack trace:
PHP 1. {main}() /index.php:0
PHP 2. require() /index.php:17
PHP 3. wp() /wp-blog-header.php:16
PHP 4. WP->main() /wp-includes/functions.php:1291
PHP 5. do_action_ref_array() /wp-includes/class-wp.php:763
PHP 6. WP_Hook->do_action() /wp-includes/plugin.php:551
PHP 7. WP_Hook->apply_filters() /wp-includes/class-wp-hook.php:316
PHP 8. WP_Customize_Widgets->customize_register() /wp-includes/class-wp-hook.php:292
PHP 9. WP_Customize_Widgets->is_wide_widget() /wp-includes/class-wp-customize-widgets.php:509

PHP Notice: Trying to access array offset on value of type null in /wp-includes/class-wp-customize-widgets.php on line 577
PHP Stack trace:
PHP 1. {main}() /index.php:0
PHP 2. require() /index.php:17
PHP 3. wp() /wp-blog-header.php:16
PHP 4. WP->main() /wp-includes/functions.php:1291
PHP 5. do_action_ref_array() /wp-includes/class-wp.php:763
PHP 6. WP_Hook->do_action() /wp-includes/plugin.php:551
PHP 7. WP_Hook->apply_filters() /wp-includes/class-wp-hook.php:316
PHP 8. WP_Customize_Widgets->customize_register() /wp-includes/class-wp-hook.php:292
PHP 9. WP_Customize_Widgets->is_wide_widget() /wp-includes/class-wp-customize-widgets.php:509