property 27of 27 does not exist on type 27typeof observable 27

1import { of } from 'rxjs';
2

1import { from } from 'rxjs';
2
3var observableFromPromise =  from(promiseSrc);
4

1import { tap } from 'rxjs/operators';
2
3const TOKEN_HEADER_KEY = 'Authorization';
4
5@Injectable()
6export class Interceptor implements HttpInterceptor {
7
8  constructor(private token: TokenStorage, private router: Router) { }
9
10  intercept(req: HttpRequest<any>, next: HttpHandler):
11    Observable<HttpSentEvent | HttpHeaderResponse | HttpProgressEvent | HttpResponse<any> | HttpUserEvent<any>> {
12    let authReq = req;
13    if (this.token.getToken() != null) {
14      authReq = req.clone({ headers: req.headers.set(TOKEN_HEADER_KEY, 'Bearer ' + this.token.getToken())});
15    }
16    return next.handle(authReq).pipe(tap(
17        (err: any) => {
18          if (err instanceof HttpErrorResponse) {
19            console.log(err);
20            console.log('req url :: ' + req.url);
21            if (err.status === 401) {
22              this.router.navigate(['user']);
23            }
24          }
25        }
26      ));
27  }
28
29}
30