用.net开发钉钉服务api，获取Token（GetAccessTokenAsync）时报错：

在获取 AccessToken 时，确保你已经正确捕获并处理了所有可能的错误和异常。

public async Task<string> GetAccessTokenAsync()
{
    string url = "https://oapi.dingtalk.com/gettoken?appkey=your_appkey&appsecret=your_appsecret";
    using (var httpClient = new HttpClient())
    {
        HttpResponseMessage response = await httpClient.GetAsync(url);

        // 确保响应成功
        response.EnsureSuccessStatusCode();

        string responseBody = await response.Content.ReadAsStringAsync();
        var tokenResponse = JsonConvert.DeserializeObject<TokenResponse>(responseBody);

        if (tokenResponse == null || tokenResponse.AccessToken == null)
        {
            throw new InvalidOperationException("Failed to retrieve access token.");
        }

        return tokenResponse.AccessToken;
    }
}

public class TokenResponse
{
    [JsonProperty("access_token")]
    public string AccessToken { get; set; }

    [JsonProperty("errcode")]
    public int? ErrCode { get; set; }

    [JsonProperty("errmsg")]
    public string ErrMsg { get; set; }
}