Transitioning from UIKit to SwiftUI with TCA: Handling Session Management and HTTP Error 4xx

[Tabonx]

I'm trying to integrate TCA into a project that used the UIKit lifecycle, and I'm changing it to SwiftUI with TCA. The project is quite a mess, and I'm new to TCA. There is a REST service that accepts requests from Providers signs them with a token stored Session singleton, and returns data from the executed request. However, when the request returns HTTP Error 4xx, it calls a function on the Session and the user is logged out. The Session also has a function var onSignOut: (() -> Void)? that is implemented in the UINavigationController class. The function switches the current screen to login.

How would I go about this in TCA?

The code essentialy looks like this

SomeProvider.swift

    // Provider
    let response: Data = try await rest.perform(request: request)

REST.swift

     // REST performs the request
     Session.shared.react(to: response.statusCode)

Session.swift

     // Session reacts
     func react(to statusCode: Int) {
        if statusCode >= 400, statusCode < 500 {
            signOut()
        }
    }

     // Session signs user out.
    func signOut() {
            token = nil
            onSignOut?()
    }

iOS 16