Incorrect return type in NgPushRegistration.log()

[maciejtreder]

In the https://github.com/angular/mobile-toolkit/blob/master/service-worker/worker/src/companion/comm.ts we can see that metho .log() returns Observable<string> wile the return type is in fact different

The output from

this.sw.log().subscribe(msg => console.log(msg));

is: