execute Find Rents By Price Command [ Stable sort ]

function executeFindRentsByPriceCommand(minPrice, maxPrice) {
    if (isNaN(minPrice) || isNaN(maxPrice)) {
        throw new Error("Invalid price range.");
    }

    var selectedOffers = _offers.filter(function (offer) {
        return offer.getPrice() >= minPrice && offer.getPrice() <= maxPrice && offer instanceof RentOffer;
    });
    selectedOffers.sort(function (a, b) {
        // stable sort
        var result = a.getPrice() - b.getPrice();
        if (result == 0) {
            result = a.getEstate().getName().localeCompare(b.getEstate().getName());
        }

        return result;
    });

    return formatQueryResults(selectedOffers);
}