Having watched Paul's latest birthday video, I've vowed to use @StateObject properly, which of course lands me in trouble almost immediately:

@main
struct ArkansasApp: App {
    @StateObject var appState = AppState()
    @StateObject var arkansasScene: ArkansasScene

    init() {
    // Problem here: compiler says "Escaping autoclosure captures mutating 'self' parameter"
    // I'm only barely grasping what the message means, so naturally I have no idea what to
    // do to fix it.
        _arkansasScene = StateObject(wrappedValue: ArkansasScene(appState: _appState))
    }

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(appState)
                .environmentObject(arkansasScene)
        }
    }
}

I was doing this with @ObservedObject before, and it was working fine, but I'm kind of fussy about doing things the right way, plus Paul says it might not always behave properly at runtime. Anyone have any advice?

_appState refers to the @StateObject property wrapper. Maybe you mean appState, which refers to the wrapped value? I don't know what the initializer for ArkansasScene looks like.