Add one product on the cart

Hello!
I would like just to allow to add one product on the cart page, so I tried with a code on my funtions.php and it worked for one week, but suddenly is not working and I don’t know why.
That’s my code:
//Just one item in cart at a time

add_filter( ‘woocommerce_add_cart_item_data’, ‘woo_custom_add_to_cart’ );

function woo_custom_add_to_cart( $cart_item_data ) {

global $woocommerce;
$woocommerce->cart->empty_cart();

// Do nothing with the data and return
return $cart_item_data;
}

Maybe there’s something wrong with my code or you can provide me a different one
Thank you

https://www.ads-software.com/plugins/woocommerce/