Angular service to get a JWT token from the token endpoint

TokenService.ts

import { OnInit, Injectable } from "@angular/core";
import { Observable } from "rxjs/Observable";
import {
  HttpClient,
  HttpHeaders,
  HttpErrorResponse
} from "@angular/common/http";
import { environment } from "../../../../environments/environment";
import { tap, catchError } from "rxjs/operators";
import { ErrorObservable } from "rxjs/observable/ErrorObservable";

@Injectable()
export class TokenizerService implements OnInit {
  ngOnInit(): void {}

  constructor(private http: HttpClient) {}

  getToken(): Observable<any> {
    const headers = new HttpHeaders({ "Content-Type": "application/json" });
    const url = `${environment.tokenapi}`;
    return this.http
      .post(
        url,
        { userName: "username", password: "password" },
        { headers: headers }
      )
      .pipe(
        tap(data => console.log("Data: " + JSON.stringify(data))),
        catchError(this.handleError)
      );
  }

  private handleError(err: HttpErrorResponse): ErrorObservable {
    let errorMessage: string;
    if (err.error instanceof Error) {
      // A client-side or network error occurred. Handle it accordingly.
      errorMessage = `An error occured: ${err.error.message}`;
    } else {
      // The backend returned an unsuccessful response code.
      // The response body may contain clues as to what went wrong,
      errorMessage = `Backend returned code ${err.status}, body was: ${
        err.error
      }`;
    }
    console.error(err);
    return new ErrorObservable(errorMessage);
  }
}