title: Enum cases with associated values cannot be marked potentially unavailable with '@available'
body: <p>I am getting an error message with <strong>Xcode 13</strong> on the following code</p>
  <pre><code>@available(iOS 13.0, *)
      case windowScene(_: UIWindowScene, windowLevel: UIWindow.Level)
  </code></pre>
  <blockquote>
  <p>Enum cases with associated values cannot be marked potentially unavailable with '@available'</p>
  </blockquote>
  <p>Does anyone know why I'm getting this error and what is the solution to rectify it? It was working fine in Xcode 12.</p>