应用程序在尝试添加导航栏后仍然崩溃

I've been following a tutorial to add a navigation bar to my app. However, prior to adding the relevant code, after registering the user, the user would be automatically logged in and redirected to the LoggedInMenu class. Since trying to create a navigation bar, the app crashes after clicking the register button.I've been following a tutorial to add a navigat