Error firestore - ios

Question

I just started to learn firestore, i created simple app like a example from googleFirestore (in github).
When i change or create new data in firestore i get an error when my app is start in this line:
fatalError("Error")
I so understand the app is not like creating new data, how can I avoid this error and create data in real time?
My code:
private var hall: [Hall] = []
private var documents: [DocumentSnapshot] = []
fileprivate var query: Query? {
didSet {
if let listener = listener {
listener.remove()
observeQuery()
}
}
}
private var listener: ListenerRegistration?
fileprivate func observeQuery() {
guard let query = query else { return }
stopObserving()
listener = query.addSnapshotListener { [unowned self] (snapshot, error) in
guard let snapshot = snapshot else {
print("Error fetching snapshot results: \(error!)")
return
}
let models = snapshot.documents.map { (document) -> Hall in
if let model = Hall(dictionary: document.data()) {
return model
} else {
fatalError("Error")
}
}
self.hall = models
self.documents = snapshot.documents
self.tableView.reloadData()
}
}
func stopObserving() {
listener?.remove()
}
func baseQuery() -> Query {
return Firestore.firestore().collection("searchStudios").limit(to: 50)
}
override func viewDidLoad() {
super.viewDidLoad()
tableView.tableFooterView = UIView()
query = baseQuery()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
self.setNeedsStatusBarAppearanceUpdate()
observeQuery()
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(true)
stopObserving()
}
override var preferredStatusBarStyle: UIStatusBarStyle {
set {}
get {
return .lightContent
}
}
deinit {
listener?.remove()
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! ResultTableViewCell
cell.populate(hall: hall[indexPath.row])
return cell
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return hall.count
}
I can delete data, but not can add new data.
UPDATE:
struct Hall:
import Foundation
protocol DocumentSerializable {
init?(dictionary: [String: Any])
}
struct Hall {
var description: String
var image: String
var meters: Double
var name: String
var price: Int
var studioHallAddress: String
var studioHallName: String
var studioHallLogo: String
var dictionary: [String: Any] {
return [
"description": description,
"image": image,
"meters": meters,
"name": name,
"price": price,
"studioHallAddrees": studioHallAddress,
"studioHallName": studioHallName,
"studioHallLogo": studioHallLogo
]
}
}
extension Hall: DocumentSerializable {
init?(dictionary: [String : Any]) {
guard let description = dictionary["description"] as? String,
let image = dictionary["image"] as? String,
let meters = dictionary["meters"] as? Double,
let name = dictionary["name"] as? String,
let price = dictionary["price"] as? Int,
let studioHallAddress = dictionary["studioHallAddress"] as? String,
let studioHallName = dictionary["studioHallName"] as? String,
let studioHallLogo = dictionary["studioHallLogo"] as? String else { return nil }
self.init(description: description,
image: image,
meters: meters,
name: name,
price: price,
studioHallAddress: studioHallAddress,
studioHallName: studioHallName,
studioHallLogo: studioHallLogo)
}
}