Flutter 当API返回400时，catch不到DioError ，总是出现throw assureDioError(e, options);

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Issue Info

| Info | Value | |
| ------------------------------ | ----------------------------------------------------- | ---- |
| Platform Name | e.g. flutter / windows10/ android | |
| Platform Version | e.g. 1.22.4 / 10 / 9.0 | |
| Dio Version | e.g. 3.0.10 | |
| Visual Studio Code Version | e.g. 1.52.1 | |
| Repro rate | e.g. all the time (100%) / sometimes x% / only once | |

Issue Description and Steps

我使用leancloud的SDK，当对方服务器返回400错误的时候，vsc 就会跳到这个页面：

dio.dart 第966行
} catch (e) {
throw assureDioError(e, options);
}
并有红色提示：
Exception has occurred.
DioError (DioError [DioErrorType.RESPONSE]: Http status error [400])

于是我跟踪到此SDK的post动作，输出一些发送的数据与参数：
SDK 的文件 lc_http_client.dart , line70:

try {
print('=====1.The params to post:====={');
print(path);
print(options);
print(data);
print(queryParams);
print('=====1.The params to post:=====}');

  Response response = await _dio.post(path,
      options: options, data: data, queryParameters: queryParams);
  return response.data;
} on DioError catch (e) {
  print('=====2.Here catch DioError:====={');
  print(e);
  print('=====2.Here catch DioError:=====}');
  _handleError(e);  //此函数可以在这里点击查看 [ _handleError(e);](https://github.com/leancloud/Storage-SDK-Flutter/blob/985f9ad91e3b1d5824fd3340c68d6010a6c606e3/lib/internal/http/lc_http_client.dart)
}

我也附上我本身的业务逻辑的代码：
try {
developer.log('======Begin :=======');
await LCSMSClient.requestSMSCode(_phoneNumber);
}on DioError catch (e){
developer.log('======DioError catch=======');
} on LCException catch (e) {
developer.log('======LCException catch=======');
developer.log(e.message);
} catch (e) {
developer.log('======catch=======');
}

输出如下：
[log] ======Begin :=======
I/flutter ( 1793): =====1.The params to post:====={
I/flutter ( 1793): requestSmsCode
I/flutter ( 1793): Instance of 'Options'
I/flutter ( 1793): {"mobilePhoneNumber":"+8625786"}
I/flutter ( 1793): null
I/flutter ( 1793): =====1.The params to post:=====}
I/flutter ( 1793): =====2.Here catch DioError:====={
I/flutter ( 1793): DioError [DioErrorType.RESPONSE]: Http status error [400]
I/flutter ( 1793): =====2.Here catch DioError:=====}
[log] ======LCException catch=======
[log] 无效的手机号码。

问题：看输出，dio.post执行之后是可以catch到DioError的，但是为什么VSC编辑器每次都会跳转到
throw assureDioError(e, options);
并有红色提示呢？

即使我改为如下，不用on DioError或改为catchError，还是会跳转到throw assureDioError(e, options);并有红色提示。

try {
developer.log('======Begin :=======');
await LCSMSClient.requestSMSCode(_phoneNumber).catchError(( /DioError/ e) {
developer.log('======I am catchError=======');
});
}catch (e) {
developer.log('======catch=======');
}
输出：
V/AudioManager( 7109): querySoundEffectsEnabled...
[log] ======Begin :=======
[log] ======I am catchError=======

这里明显可以catch到，但为什么还会在throw assureDioError(e, options);里面抛出来呢？求大侠指导！
（已在github提出问题，希望尽快得到答复，谢谢：https://github.com/leancloud/Storage-SDK-Flutter/issues/98）