我正在使用AWS Cognito进行身份验证，并为移动（Xamarin.Forms）和Web（Blazor Webassembly）构建了相同的服务。 当我尝试注册已经注册的用户时，它应该抛出AliasExistsException或usernameExistsException，它可以在Xamarin和小型Win32-ConsoleApp中进行测试，但是在Blazor上会发生无法捕获的Http-400例外。

这是我的代码：

public async Task Register()
{
    // here the variables are defined,omitted for brevity
    try
    {
        var signUpRequest = new SignUpRequest()
                {
                    username = username,Password = password,ClientId = clientId,UserAttributes = CognitoAuthHelper.CreateAttributeList(userAttributes),ValidationData = null,SecretHash = CognitoAuthHelper.GetUserPoolSecretHash(username,clientId,clientSecret)
                };                    
                var signUpResponse = await client.SignUpAsync(signUpRequest).ConfigureAwait(false);
     }
     catch (AliasExistsException)
     {
          CognitoResult = new CognitoResult(CognitoResultType.usernameAlreadyUsed);
     }
     catch (usernameExistsException)
     {
         CognitoResult = new CognitoResult(CognitoResultType.EmailAlreadyUsed);
     }
     catch (Exception exc)
     {
         Console.WriteLine(exc);
     }
}

Chrome控制台会打印以下内容：

mono.js:1 Fetch finished loading: OPTIONS "https://cognito-idp.eu-central-1.amazonaws.com/".
_mono_wasm_invoke_js_with_args @ mono.js:1
(anonymous)
...
(anonymous)
Module._mono_wasm_invoke_method @ mono.js:1
callMethod @ blazor.webassembly.js:1
beginInvokeDotNetFromJS @ blazor.webassembly.js:1
u @ blazor.webassembly.js:1
e.invokeMethodAsync @ blazor.webassembly.js:1
(anonymous) @ blazor.webassembly.js:1
t.dispatchEvent @ blazor.webassembly.js:1
(anonymous) @ blazor.webassembly.js:1
(anonymous) @ blazor.webassembly.js:1
e.onGlobalEvent @ blazor.webassembly.js:1
Show 99 more frames
cognito-idp.eu-central-1.amazonaws.com/:1 POST https://cognito-idp.eu-central-1.amazonaws.com/ 400

有什么建议吗？也许这也是一个mono.js问题？