I've noticed that if I add another field of GMSPlaceField to my request like the one demonstrated here: https://developers.google.com/places/ios-sdk/client-migration#fetch_a_place_photo
and say make the fields like so:
let fields: GMSPlaceField = GMSPlaceField(rawValue: UInt(GMSPlaceField.name.rawValue) | UInt(GMSPlaceField.photos.rawValue))!
fields results to an invalid instance of GMSPlaceField:
GMSPlaceField <invalid>
hence the request fails