[NT-551] Crash on logout fix

[Scollaco]

📲 What

• Fixes a bug where the app crashes when user tries to logout.
• The crash started happening after the PR that navigates from Project Page was merged. We were returning a viewController of type T from the function viewControllerAndParam<T, P>(with :param:) -> (T, P)? when we should be returning nil.

🤔 Why

• Crashes are a no no.

🛠 How

• Determining on RootTabBarViewController if we are switching to Dashboard.

If yes:

• We try to cast the viewController[index] to UINavigationController and then cast its first child to type T.

If no:

• We try to cast the viewController[index] to type T directly.

We return nil otherwise.

👀 See

[justinswart]

Can we make this small change for readability:

guard
  let vcs = self.viewControllers,
  let nav = vcs[clamp(0, vcs.count - 1)(index)] as? UINavigationController,
  let vc = nav.children.first as? T
else { return nil }