I’m sort of surprised that the error isn’t on this.loginForm.username and this.loginForm.password. I thought those had to hang off of controls, like this.loginForm.controls.username.
As a side note, your service methods use the explicit promise constructor antipattern. I see this particular boilerplate a lot on these forums, so I assume that it comes from some sort of generator. If anybody knows exactly which driftyco project it comes from, I’ll open an issue about it. Bottom line: it probably makes the most sense to just return the underlying Observable. If you really really want a Promise instead, use Observable.toPromise instead of creating a Promise from scratch.