        // If the `_refundRecipient` is not provided, we use the `_sender` as the recipient.
        address refundRecipient = _refundRecipient == address(0) ? _sender : _refundRecipient;
        // If the `_refundRecipient` is a smart contract, we apply the L1 to L2 alias to prevent foot guns.
        if (refundRecipient.code.length > 0) {
            refundRecipient = AddressAliasHelper.applyL1ToL2Alias(refundRecipient);
        }
+       require(refundRecipient > address(0xFFFF), "You can't send your pennies to the kernel");
