Angular 4 - Observable catch error

Question

How can I solve the problem of return with error, use the capture inside the Observable?

I want to execute a function inside the catch, to do some validation before the subscribe is executed.

Thank you in advance, thank you very much for your attention.

Error occurs in -> .catch( (e) => {console.log(e)} )

import { Injectable } from '@angular/core';
import { Headers, Http, ResponseOptions} from '@angular/http';
import { AuthHttp } from 'angular2-jwt';

import { MEAT_API } from '../app.api';

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class  CompareNfeService {


    constructor(private http: AuthHttp) { }

    envirArquivos(order): Observable<any> {
        const headers = new Headers();
        return this.http.post(`${MEAT_API}compare/arquivo`, order,
        new ResponseOptions({headers: headers}))
        .map(response => response.json())
        .catch( (e) => {console.log(e)} );
    }
}

Error

ERROR in /XXXXXX/application/src/app/compare/service.ts (28,17): Argument of type '(e: any) => void' is not assignable to parameter of type '(err: any, caught: Observable) => ObservableInput<{}>'.
Type 'void' is not assignable to type 'ObservableInput<{}>'.

Answer 1

If you want to use the catch() of the Observable you need to use Observable.throw() method before delegating the error response to a method

import { Injectable } from '@angular/core';
import { Headers, Http, ResponseOptions} from '@angular/http';
import { AuthHttp } from 'angular2-jwt';

import { MEAT_API } from '../app.api';

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class CompareNfeService {


  constructor(private http: AuthHttp) {}

  envirArquivos(order): Observable < any > {
    const headers = new Headers();
    return this.http.post(`${MEAT_API}compare/arquivo`, order,
        new ResponseOptions({
          headers: headers
        }))
      .map(response => response.json())
      .catch((e: any) => Observable.throw(this.errorHandler(e)));
  }

  errorHandler(error: any): void {
    console.log(error)
  }
}