App Level Error Handler in Angular

AppErrorHandler.ts

import { AppDataService, AppNotificationService } from '../services';
import { AppError } from '../entities';
import { Injectable, Injector, ErrorHandler } from '@angular/core';


@Injectable()
export class AppErrorHandler implements ErrorHandler {

  constructor(private injector: Injector) { }


  handleError(error) {
  
    //As AppErrorHandler would be loaded before AppDataService, hence we cannot insantiate AppDataService in constructor 
    //so get AppDataService using injector
    const dataService = this.injector.get(AppDataService);

    const errorMessage = error.message || 'Unknown error thrown. Please see stack';

    // post the error to the server logs 
    dataService.addToLog({ title: errorMessage, description: error.stack });
    
    // when throwing errors anywhere in app in try/catch blocks, we cast the error as AppError. 
    // AppError is a type to store error details 
    if (error instanceof AppError){
      if (error.notifyUser){ //if user needs to be informed 
         const appNotificationService = this.injector.get(AppNotificationService);
         appNotificationService.set({ type: error.type, message: error.message });
      }
    }
    
    throw appError;
  }
  
}