Throwable

class Throwable
{
    private:
    union
    {
        ExceptionOrOtherShitIndicatesError exc;
        SomeValueIndicatesSuccess successCode;
    }

    public:
    bool isError() { // Tells if exception is stored in union };
    auto getError() -> ExceptionOrOtherShitIndicatesError {};
    auto getSuccessCode() -> SomeValueIndicatesSuccess {};

    static ExceptionOrOtherShitIndicatesError constructError() {};
    static SomeValueIndicatesSuccess createSuccessThrow() {};
};