if (maxCollateral > dueOut.collateral) {
    uint256 excess;
    unchecked {
        excess -= dueOut.collateral;
    }
    ETH.transfer(payable(msg.sender), excess);
}
struct Due {
    uint112 debt;
    uint112 collateral;
    uint32 startBlock;
}
if (maxCollateral > dueOut.collateral) {
    uint256 excess = maxCollateral;
    unchecked {
        excess -= dueOut.collateral;
    }
    ETH.transfer(payable(msg.sender), excess);
}
