angular-error-handing.ts

// errors-handler.ts
import { ErrorHandler, Injectable} from '@angular/core';
import { HttpErrorResponse } from '@angular/common/http';
@Injectable()
export class ErrorsHandler implements ErrorHandler {
  handleError(error: Error | HttpErrorResponse) {   
   if (error instanceof HttpErrorResponse) {
      // Server or connection error happened
      if (!navigator.onLine) {
        // Handle offline error
      } else {
        // Handle Http Error (error.status === 403, 404...)
      }
   } else {
     // Handle Client Error (Angular Error, ReferenceError...)     
   }
  // Log the error anyway
  console.error('It happens: ', error);
}

handler-error.ts

// errors-handler.ts
@Injectable()
export class ErrorsHandler implements ErrorHandler {
  constructor(
       // Because the ErrorHandler is created before the providers, we’ll have to use the Injector to get them.
       private injector: Injector,
   ) { }
  handleError(error: Error | HttpErrorResponse) {
  
   const notificationService = this.injector.get(NotificationService);
   if (error instanceof HttpErrorResponse) {
      // Server or connection error happened
      if (!navigator.onLine) {
        // Handle offline error
        return notificationService.notify('No Internet Connection');
      } else {
        // Handle Http Error (error.status === 403, 404...)
        return notificationService.notify(`${error.status} - ${error.message}`);
      }
   } else {
     // Handle Client Error (Angular Error, ReferenceError...)     
   }
  // Log the error anyway
  console.error('It happens: ', error);
}

more-handler-error.ts

// errors-handler.ts
@Injectable()
export class ErrorsHandler implements ErrorHandler {
constructor(
   private injector: Injector
) { }
handleError(error: Error | HttpErrorResponse) {
  
   const notificationService = this.injector.get(NotificationService);
   const router = this.injector.get(Router);
if (error instanceof HttpErrorResponse) {
      // Server or connection error happened
      if (!navigator.onLine) {
        // Handle offline error
        return notificationService.notify('No Internet Connection');
      } else {
        // Handle Http Error (error.status === 403, 404...)
        return notificationService.notify(`${error.status} - ${error.message}`);
      }
   } else {
     // Handle Client Error (Angular Error, ReferenceError...)
     router.navigate(['/error'], { queryParams: {error: error} });
   }
  // Log the error anyway
  console.error('It happens: ', error);
}