Грохот во время сеанса и увольнения

У меня проблема, мое приложение рушится во время segue в моем TableViewController

import UIKit
import MapKit
import CoreLocation

class CourseClass: UITableViewController, CLLocationManagerDelegate, MKMapViewDelegate {

    @IBOutlet weak var map: MKMapView!

    struct User {

        var name: String
        var images: UIImage
        var coordinate: (Double, Double)
        var type: String
    }

    /* var place = ["Caffè Spagar", "Duks", "Posta station", "Barnum", "Elephant Club", "Cinema", "Space", "Andromeda", "Rodolf", "Devil Chair"] */

    var rows = 0
    var users = [User]()

    let CS = User(name: "Caffè Spagar", images: UIImage(named: "Caffè Spagar.png")! , coordinate:(12345,54678), type: "Pub")
    let D = User(name: "Duks", images: UIImage(named: "Duks.png")! , coordinate:(13345,54128), type: "Shopping")
    let PS = User(name: "Posta station", images: UIImage(named: "Posta station.png")! , coordinate:(18795,34556), type: "Resturant")
    let B = User(name: "Barnum", images: UIImage(named: "Barnum.png")! , coordinate:(46655,43554), type: "Pub")
    let EC = User(name: "Elephant Club", images: UIImage(named: "Elephant Club.png")! , coordinate:(12325,21435), type: "Disco")
    let C = User(name: "Cinema", images: UIImage(named: "Cinema.png")! , coordinate:(11235,12343), type: "Cinema")
    let S = User(name: "Space", images: UIImage(named: "Space.png")! , coordinate:(12345,66432), type: "Cinema")
    let A = User(name: "Andromeda", images: UIImage(named: "Andromeda.png")! , coordinate:(64545,23443), type: "Sport")
    let R = User(name: "Rodolf", images: UIImage(named: "Rodolf.png")! , coordinate:(64545,34358), type: "Shopping")
    let DC = User(name: "Devil Chair", images: UIImage(named: "Devil Chair.png")! , coordinate:(56656,54678), type: "Shopping")

    override func viewDidLoad() {
        super.viewDidLoad()

        map.showsUserLocation = true
        map.delegate = self

        users.append(CS)
        users.append(D)
        users.append(PS)
        users.append(B)
        users.append(EC)
        users.append(C)
        users.append(S)
        users.append(A)
        users.append(R)
        users.append(DC)
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        insertRowsMode3()
    }

    func insertRowsMode2() {

        for i in 0..<users.count {
            insertRowMode2(ind: i, usr: users[i])
        }

    }

    func insertRowMode2(ind:Int,usr:User) {

        let indPath = IndexPath(row: ind, section: 0)

        rows = ind + 1
        tableView.insertRows(at: [indPath], with: .right)
    }

    func insertRowsMode3() {

        rows = 0

        insertRowMode3(ind: 0)
    }

    func insertRowMode3(ind:Int) {
        let indPath = IndexPath(row: ind, section: 0)
        rows = ind + 1
        tableView.insertRows(at: [indPath], with: .right)

        guard ind < users.count-1 else { return }
        DispatchQueue.main.asyncAfter(deadline: .now()+0.15) {

            self.insertRowMode3(ind: ind+1)
        }
    }    

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return rows
    }

    public override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

      let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! MyTableViewCell

      let user = users[indexPath.row]

        cell.myImage.image = user.images
        cell.myLabel.text = user.name
        cell.myTypeLabel.text = user.type

    /*  cell.myImage.image = UIImage(named: (place[indexPath.row] + ".png"))
        cell.myLabel.text = place[indexPath.row]
    */

        return (cell)
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

       performSegue(withIdentifier: "goToLast" , sender: users[indexPath.row])

    }

    override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 100
    }

    @IBAction func mapTapped(_ sender: Any) {

    let userLocation = map.userLocation

    let region = MKCoordinateRegionMakeWithDistance((userLocation.location?.coordinate)!,2000,2000)       
    map.setRegion(region, animated: true)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "goToLast" {

        guard let vc = segue.destination as? FinalClass else { return }

        let guest = segue.destination as! FinalClass

              guest.local = sender as! String

             guest.localImage = UIImage(named: (sender as! String) + ".png")!     
            guest.localType = sender as! String            
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }    
}

именно в этой функции

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "goToLast" {           
        guard let vc = segue.destination as? FinalClass else { return }

        let guest = segue.destination as! FinalClass

              guest.local = sender as! String

             guest.localImage = UIImage(named: (sender as! String) + ".png")!            
            guest.localType = sender as! String       
    }
}

И проблема

Не удалось передать значение типа "Myapp.CourseClass.User" в "Swift.String".

Кроме того, перед тем как испытать эту проблему, приложение рушилось, когда я увольняю следующую сцену, чтобы вернуться сюда. Кто-то знает, как я могу настроить свой код, чтобы он работал?