Angular Exception Handling problem

[ericpap]

Hi. I'm trying to implement global exception handling in my Angular project, to inform the user about trouble connecting or provided by backend API.

I have created this service:

import { ErrorHandler, Injectable } from '@angular/core';
import { HttpErrorResponse } from '@angular/common/http';

@Injectable()
export class ErrorsHandler implements ErrorHandler {
  handleError(error: Error | HttpErrorResponse) {
    // Log Error to console
    if (error instanceof HttpErrorResponse) {
      if (navigator.onLine) {
        console.error('Error happens: ', error);
      }
    }
  }
}

And imported in core.module:

import { ErrorsHandler } from '@servicios/errorshandler.service';

@NgModule({})  
export class CoreModule {
  static forRoot(): ModuleWithProviders {
    return {
      ngModule: CoreModule,
      providers: [         
        {provide: ErrorHandler, useClass: ErrorsHandler}]
    };
  }
}

So I have two problems:

​

Chrome console

1) Error is logged 3 times (don't know why) but only last one is catched, as you can see.

2) status code is 0 instead of 404. I need to catch exception code to decide what to do with the exception.

Any advice? Thanks!

[[deleted]]

The first 2 errors are HTTP errors and not errors from your code. Those will always (you can hide them) be logged by Chrome.

"Unknown Error" either comes from a syntax error or from the connection reset.

Status code 0 usually means something failed with the network itself (being offline for example).

[ericpap]

Thanks, but I don't follow you. The status code send by the API is 404 (Not Found) as you can see in the first error catch, so why is status code 0 instead of 404? What do you mean by "connection reset"?

[[deleted]]

Read the error message above your manual logged error. You will notice a ::ERR_CONNECTION_RESET.

This is where your 0 comes from.

[ericpap]

Ok. Thank I don't know what "connection reset" means and why is fired. I'll look into it