Impossible to connect while my code has no errurs in ionic

Hello, I have a small project that I develop on ionic 3 and Angular 5. I create my login page and my service, when I click on the ‘login’ button, I have a validated return on the browser side .
but I can not connect. Your help please

Code : AuthService.ts

Code : Login.ts

Result in navigator :

But I can not connect to the application !