How to Fix Undefined array key “action” on WordPress site running on Php8

I’m getting error PHP message: PHP Warning: Undefined array key "action" for this code:

function disable_lost_password() {     if ( in_array( $  _GET['action'], array('lostpassword', 'retrievepassword') ) ) {         wp_redirect( wp_login_url(), 301 );         exit;     } } add_action( "init", "disable_lost_password" ); 

How to fix it?