Xcode – Constraints on storyboard not allowing code to run

I am creating a quiz app as a school project, but when I am creating the questions there was a problem that occurred. The quiz itself works, but as soon as I added constraints to the buttons on the storyboard, there some issues which occurred, and I want to know if I can get some help? The code is as follows, and is in the language of swift:

class MathsViewController: UIViewController {
    

    let questions = ["What is the turning point of the graph, y = x^2 + 8x + 6 ?", "What are the x-intercepts of the graph, y = x^2 + 11x + 18 ?", "What is the triganomic ratio used when relating the opposite and adjacent?", "What would be the final form of the equation, 14/x = sin(20) ?", "Which equation, would have the steepest slope?", "If we added every positive whole number, what would the solution be?", "Which of the following is the fibonacci sequnce?", "What are the first 10 digits of pi?", "What is the probability of getting a 6 in all your rolls, when rolling a dice 3 times?", "If the hypostenuse of a triangle is 26cm, and a side edge is of 10cm long. What is the length of the other side?"]
    

    let answers = [["(-4, -10)", "(0,0)", "(-6, -1)"], ["x = -2 or x = -9", "x = 18 or x = 11", "x = 9 or x = 2"], ["tan", "cos", "sin"], ["x = 14/sin(20)", "x = 14sin^-1/20", "x = sin^-1(20)"], ["y = 5x+2", "y = 1/3x+4", "y = x+16"], ["-1/12", "infinity", "0"], ["1,1,2,3,5,8,13", "1,2,3,4,5,6,7", "1,1,2,2,4,8,32"], ["3.1415926535", "3.141533536", "3.1415934435"], ["1/216", "1/36", "1/6"], ["24cm", "28cm", "26cm"]]
    

    //Variables
    var currentQuestion = 0
    var rightAnswerPlacement = 0
    var points = 0;
    

    //Label
    @IBOutlet weak var Label: UILabel!
    

    //Button
    @IBAction func action(_ sender: Any)
    {
        if (sender as AnyObject).tag == Int(rightAnswerPlacement)
        {
            print("RIGHT!")
            points += 1
        }
        else
        {
            print("WRONG!!!")
        }
        

        if (currentQuestion != questions.count)
        {
            newQuestion()
        }
        else
        {
            performSegue(withIdentifier: "showScore", sender: self)
        }
        print(points)
    }
    

    

    override func viewDidLayoutSubviews() {
        newQuestion()
    }
    

    //Function that displays new question
    func newQuestion()
    {
        Label.text = questions[currentQuestion]
        

        rightAnswerPlacement = Int(arc4random_uniform(3)+1)
        

        //Create Button
        var button:UIButton = UIButton()
        

        var x = 1
        

        for i in 1...3
        {
            //Create a button
            button = view.viewWithTag(i) as! UIButton
            

            if (i == Int(rightAnswerPlacement))
            {
                button.setTitle(answers[currentQuestion][0], for: .normal)
            }
            else
            {
                button.setTitle(answers[currentQuestion][x], for: .normal)
                x = 2
            }
        }
        currentQuestion += 1
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    


}

Here are some images of the error message:

The code with the error message

Error Message in the debug area

Furthermore, here are some images of my storyboard to help you visualise:

Quiz interface

Final Screen

The final screen is blank with a single label, this is the screen which comes up after the quiz is complete, I need to code it so the score will replace the label.

Any help is appreciated.

Thank you in advance!