How to add listener to Firestore Geoquery?

I'm following along with the official Firestore docs to create an app using geohashes and geoqueries (https://firebase.google.com/docs/firestore/solutions/geoqueries#query_geohashes)

I'm trying to add a listener to that query but I get the following error: Declared closure result 'ListenerRegistration' is incompatible with contextual type 'Query'. I'm stumped because XCode recommends I replace "Query" with "Query" :D

All I did was add this listener to the sample code I linked above:

var queries = queryBounds.map { bound -> Query in
  return db.collection("cities")
    .order(by: "geohash")
    .start(at: [bound.startValue])
    .end(at: [bound.endValue])
    .addSnapshotListener { querySnapshot, error in
            guard let documents = queries?.documents else {
                print("Error fetching documents: \(error!)")
                return
            }
            let cities = documents.map { $0["name"]! }
            print("Current cities in CA: \(cities)")
        }
    }