import * as Rxjs from 'rxjs' ; import * as op from 'rxjs/operators' ; export function play ( ... args ) { const numbers$ = Rxjs . of ( 10 , 20 , 30 , 40 , 50 ) ; const observable$ = numbers$ . pipe ( op . map ( _ => { throw new Error ( 'Errorrrr' ) ; } ) ) ; return observable$ ; }