How to stop SwiftUI Previews from crashing when using Firebase

ExampleApp.swift

protocol FirebaseService {
    func configure()
}

class RealFirebaseService: FirebaseService {
    func configure() {
        FirebaseApp.configure()
        let settings = FirestoreSettings()
        Firestore.firestore().settings = settings
    }
}

class MockFirebaseService: FirebaseService {
    func configure() {
        // Do nothing because mocks do not use Firebase.
    }
}

class AppViewModel: ObservableObject {
    @Injected var firebaseService: FirebaseService

    init() {
        firebaseService.configure()
    }
}

@main
struct ExampleApp: App {
    @StateObject var viewModel = AppViewModel()

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}