Cannot read property 'unsubscribe' of undefined in Angular 2

I am trying to create an ObservableTimer that ticks up to a certain number. I already have logic to do that, but when I try to unsubscribe from it, I get a "Cannot read property 'unsubscribe' of undefined" error for it.

Here is my code:

syncExpireTime() {
let route = AppSettings.API_ENDPOINT + 'Account/ExpireTime'
this.http.get(route, this.options).map(this.extractData).catch(this.handleError).subscribe(
res => {this.expireTime = +res},
error => console.log(error),
() => this.timerSub = TimerObservable.create(0,1000)
.takeWhile(x => x <= this.expireTime)
.subscribe(x => x == this.expireTime ? this.logout() : console.log(x))
)
}


And then, here is my logout code. I am trying to unsubscribe from the expiration timer when I log out

logout() {
this.timerSub.unsubscribe()
this.router.navigate(['./login'])
}

Continue reading...