带有SwiftUI的NavigationLink：表达式类型不明确，没有更多上下文

我正在尝试使用我制作的按钮导航到另一个视图。我为其他视图完成了此操作，但是将其应用于下一个视图时，显示错误“表达式类型在没有更多上下文的情况下是模棱两可的”。我从其他人那里读到，SwiftUI中的错误有时不会出现在正确的行上，而可能发生在其他地方。

这是我编写的与NavigationLink一起使用的代码

struct ContentView: View {
    @State private var isActive: Bool = false
    @State private var username: String = ""
    @State private var email: String = ""
    @State private var password: String = ""

    var body: some View {

        NavigationView{
            VStack {
                NavigationLink(destination: signUp(), isActive: self.$isActive) {
                    Text("")
                }

                Image("versLogo")
                    .resizable()
                    .frame(width: 400, height: 400)
                TextField("Username", text: $username)
                TextField("Email", text: $email)
                TextField("Password", text: $password)


                Button(action: {}) {
                    Text("Login")
                }
                Spacer()
                //button for moving to next view
                Button(action: {
                    self.isActive = true
                }) {
                    Text("Don't have an account?")
                }

            }//VStack
        }//nav
    }
}

现在，这是我编写的以相同方式应用它的代码，但是却给了我这个错误。NavigationLink中的文本没有任何内容，因为我使用的是按钮，所以将其留空。

struct signUp: View {
    @State var isShowingImagePicker = false
    //for the next view
    @State private var isActive: Bool = false

    @State private var username: String = ""
    @State private var email: String = ""
    @State private var password: String = ""
    @State private var confirm: String = ""


    var body: some View {
        NavigationLink{
            VStack {
                NavigationLink(destination: DOB_finalSignUp(), isActive: self.$isActive) {
                    Text("") //ERROR is on this line
                }

                Image(uiImage: UIImage())
                    .frame(width: 200, height: 200)
                    .border(Color.black, width: 1)

                Button(action: {
                    self.isShowingImagePicker.toggle()
                }, label:  {
                    Text("Select Image")
                })


                TextField("Username", text: $username)
                TextField("Email", text: $email)
                TextField("Password", text: $password)
                TextField("Confirm Password", text: $confirm)

                //button for moving to next view
                Button(action: {
                    self.isActive = true
                }) {
                    Text("Continue")
                }
            }//VStack
        }//nav
    }
}