HttpClient.GetAsync(. .)“deadlock"当没有互联网连接时

最近我在使用System.Net.http.HttpClient().GetAsync(…)

在GetAsync(..)的中间过程中，如果我断开互联网连接，应用程序就像死锁一样，没有异常捕获，即使我等待几分钟。

这是示例代码:

private async Task<WriteableBitmap> loadImageAsync(string url)
{
    using (var httpClient = new HttpClient())
    {
        //When this line of code start execute, immediately disable the internet connection
        var response = await httpClient.GetAsync(url);
        //Once it get stuck at GetAsync(..), it won't execute the codes below
        byte[] imageByte = await response.Content.ReadAsByteArrayAsync();
        WriteableBitmap bitmap = new WriteableBitmap(1920, 1080);
        using (InMemoryRandomAccessStream randomStream = new InMemoryRandomAccessStream())
        {
            using (DataWriter writer = new DataWriter(randomStream))
            {
                writer.WriteBytes(imageByte);
                await writer.StoreAsync();
                await writer.FlushAsync();
                writer.DetachStream();
            }
            randomStream.Seek(0);
            await bitmap.SetSourceAsync(randomStream);
        }
        return bitmap;
    }
}

我曾尝试设置超时到httpClient，但它不会关心我设置什么，如果没有互联网连接。

是否有办法抓住如果互联网连接断开，或者我错过了什么?

Edit:另一个等待loadImageAsync(..)的异步任务

public async Task GetImagesAsync()
{
    //skip if image is currently loading
    if (IsImageLoading) { return; }
    IsImageLoading = true;
    ImageObjs.Clear();
    try
    {
        int numberOfLoad = (int)((double)_LocalSettings.Values[NUMBER_OF_IMAGE_LOAD_SETTINGS]);
        string region = _LocalSettings.Values[REGION].ToString();
        #region Get Bing Image info
        string jsonString = await new HttpClient().GetStringAsync($"http://www.bing.com/HPImageArchive.aspx?format=js&n={numberOfLoad}&mkt={region}");
        ImageCollection imageCollection = JsonConvert.DeserializeObject<ImageCollection>(jsonString);
        #endregion
        #region Download images
        foreach (var i in imageCollection.images)
        {
            string url;
            if (Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.UI.ViewManagement.StatusBar"))
            {
                url = i.url.Replace("1920x1080", "1080x1920");
            }
            else
            {
                url = i.url;
            }
            ImageObjs.Add(new ImageObj(await loadImageAsync(bingLink + url), i.copyright, url, i.copyrightlink, region));
        }
        showToastNotification(_MainViewModel.ImageObjs.Count.ToString() + " images loaded.");
        #endregion
    }
    catch
    {
        //if connection failed
    }
    finally
    {
        IsImageLoading = false;
    }
}

var tokenSource = new CancellationTokenSource();
tokenSource.CancelAfter(TimeSpan.FromSeconds(15));
try
{
    var response = await httpClient.GetAsync(url, tokenSource.Token);
}
catch (TaskCanceledException ex)
{
    // handle timeout here
}