Modern C++ errors

#include "pixel/pixel.hpp"
#include <exception>
#include <iostream>

namespace {
void print(pixel::Pixel value) {
    std::cout << static_cast<int>(value.red) << ' '
              << static_cast<int>(value.green) << ' '
              << static_cast<int>(value.blue) << '\n';
}
}

int main() {
    try {
        pixel::Pixel current{12, 34, 56};
        const auto accepted = pixel::replace_pixel(current, {0.0, 0.25, 1.0});
        if (!accepted) {
            std::cerr << "Unexpected failure: " << pixel::describe(accepted.error().reason) << '\n';
            return 1;
        }
        std::cout << "accepted: ";
        print(current);
        const auto rejected = pixel::replace_pixel(current, {0.0, 1.5, 1.0});
        if (rejected) {
            std::cerr << "Invalid candidate was accepted\n";
            return 1;
        }
        std::cout << "rejected channel " << rejected.error().channel << ": "
                  << pixel::describe(rejected.error().reason) << '\n';
        std::cout << "still: ";
        print(current);
        std::cout.flush();
        return std::cout ? 0 : 1;
    } catch (const std::exception& error) {
        std::cerr << "Application failure: " << error.what() << '\n';
        return 1;
    }
}