public async Task <IActionResult> OnGetAsync(Guid id)
        {
            GiftCard = await _repository.FindGiftCardAsync(id)
                       ?? throw new InvalidOperationException("Gift card not found");

            return(Page());
        }
        public async Task <IActionResult> OnGetAsync(Guid id, int maxVersion, string ignoreSnapshot = "off", int version = -1)
        {
            MaxVersion     = maxVersion;
            IgnoreSnapshot = ignoreSnapshot == "on";
            GiftCard       = await _repository.FindGiftCardAsync(id, IgnoreSnapshot, version)
                             ?? throw new InvalidOperationException("Gift card not found");

            return(Page());
        }