Open3
[Assert] UINavigationBar decoded as unlocked

[Assert] UINavigationBar decoded as unlocked for UINavigationController, or navigationBar delegate set up incorrectly. Inconsistent configuration may cause problems.
これ、どうしたらいいのか

そこによれば、
A temporary solution is to use code rather than storyboards to create the navigation controller.
storyboardでなく、コードで書けば直るって

公式のスレ