Angular 6 error handlig - HttpErrorResponse has undefined status

Question

I have a Angular 6 client consuming a REST Api developed with .Net Web Api.

Everything is working except for the error handling. When I try to process the error to react differently to different status codes (404, 403, 409, 500...) I simply can't make it work. The HttpErrorResponse object doesn't have any of the fields it is supposed to (like 'status' or 'error').

I've made a super simple service that reproduces the issue:

Request on the service.ts

 public test(): Observable<any> {
    let url = this.templatesUrl + '/myMethod';
    console.log('GET myMethod ' + url);

    return this.http.get<any>(url)
                      .pipe(catchError(this.handleError));
  }

Error handler (pretty much straight from the official documentation):

 private handleError(error: HttpErrorResponse) {
    console.warn(error);

    if (error.error instanceof ErrorEvent) {
      // A client-side or network error occurred. Handle it accordingly.
      console.error('An error occurred:', error.error.message);
    } else {
      // The backend returned an unsuccessful response code.
      // The response body may contain clues as to what went wrong,
      console.error(
        `Backend returned code ${error.status}, ` +
        `body was: ${error.message}`);
    }
    // return an observable with a user-facing error message
    return throwError('Unexpected error');
  }

Service on the .Net side:

[HttpGet]
[Route("myMethod")]
public IHttpActionResult myDotNetMethod()
{
    return InternalServerError(new Exception("Details about the issue"));
}

The service is called and it returns a status code 500 along with a json object:

The status of the response:

The response header, it is json:

The json object:

And what the log shows: no status and pretty much an empty object:

Loosk like the HttpErrorResponse is pretty much empty. But the response from the API was fine, the status code is there and the json object too.

What am I missing?

Update: In case you are wonder what hides behind that "Internal Server Error" that shows in the log (it is just the callstack generated by chrome):

Update 2: Here's the error object under the microscope. It is simply "Internal Server Error". No trace of status or message.

Answer 1

Solved... the object was empty due to an interceptor. So if something similar is happening to you check those out.

I'm sorry to have wasted everyone's time, I was unaware of the existance of that particular interceptor.

Answer 2

I think your problem is how you are throwing the error in .Net. Try this:

var statusCode = HttpStatusCode.InternalServerError;

var response = new HttpResponseMessage(statusCode)
{
    Content = new ObjectContent<object>(
        new
        {
            Message = "Error Message",
            ExceptionMessage = "StackTrace"
        },
        new JsonMediaTypeFormatter())
};

throw new HttpResponseException(response);

Or if it does not work try this: https://stackoverflow.com/a/28589333/8758483

Another good idea is to centralize your error handling by implementing an ErrorHandler in Angular.

import { ErrorHandler } from '@angular/core';

@Injectable()
export class GlobalErrorHandler implements ErrorHandler {  
  handleError(error) {
    // your custom error handling logic    
  }
}

Then you tell Angular you want to use this class instead of the default one by providing it in you NgModule:

@NgModule({   
  providers: [{provide: ErrorHandler, useClass: GlobalErrorHandler}]
})

If you want more detail you can read this article:

• Expecting the Unexpected — Best practices for Error handling in Angular

Answer 3

In the response the property is called "Message" and not "message".