erro com Thread

O que é Thread 1:breakpoint 1,1? Sempre que rodo meu código ele chega até a tela de inserção mas na hora de inserir para nesse erro,

ViewController

class ViewController: UIViewController  {

    @IBOutlet var nameField : UITextField?
    @IBOutlet var happinessField : UITextField?
    var delegate : ViewControllerDelegate?

    @IBAction func add() {
        if(nameField == nil || happinessField == nil) {
            return
        }

        let name:String = nameField!.text!

        if let happiness = Int(happinessField!.text!) {
            let meal = Meal(name: name, happiness: happiness)

            print("eaten \(meal.name) with happiness \(meal.happiness)!")

            if (delegate == nil) {
                return
            }

            delegate!.add(meal) # o erro ocorre nessa linha 


            if let navigation = navigationController {
                navigation.popViewController(animated: true)
            }
        }
    }