Deactivating WP_Widget_Recent_Comments kills the whole Widgets area

[madeinua]

This expression makes the Widgets page empty:

unregister_widget( 'WP_Widget_Recent_Comments' );

Were no problems with WordPress 5.8.

[rafiahmedd]

I was trying to recreate the issue in the latest 5.9 however I am unable to do this. Could you please add some more details on this?

[madeinua]

This may be the problem with my customized theme. But what I found is that this part:

functions.php

remove_action('init', 'wp_widgets_init', 1);
add_action('init', static function () {
	register_widget( 'WP_Nav_Menu_Widget' );
	do_action( 'widgets_init' );
}, 1);

Throws this error:

Warning: foreach() argument must be of type array|object, null given in \wp-includes\widgets.php on line 1552