Geolocation watchPosition errors

[Jahrenski]

I'm submitting a ... (check one with "x")
[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://forum.ionicframework.com/ or https://ionicworldwide.herokuapp.com/

Current behavior:
It is currently impossible to handle PositionErrors occuring in the success path of the watchPosition observable. The only thing you can do is ignore them.

Expected behavior:
I expect errors to use the error path of the subscriber OR that we use a union type of Geoposition|PositionError

Related code:

this.geolocation.watchPosition({ enableHighAccuracy:false, timeout:10000, maximumAge:10000 }).subscribe( pos => { 
  
  if( ( pos as Geoposition ).coords ) {
    console.log( pos );
  } else {
    var positionError = (pos as PositionError); //Compiling error : Type 'Geoposition' cannot be converted to type 'PositionError'. Property 'code' is missing in type 'Geoposition'.
    console.log( positionError );
  }
}, positionError => {
  console.log( positionError );
});

Other information:
Also the documentation is outdated. You can't unsubscribe from watchPosition as observables don't have the unsubscribe method anymore. You need to use takeUntil().

"@angular/common": "^5.0.1",
"@ionic-native/core": "^4.4.0",
"@ionic-native/geolocation": "^4.4.2"