Swift UI sample of layout bug

Sample.swift

import SwiftUI

struct Sample: View {
    var body: some View {
      NavigationView {
        WebView(url: URL(string: "https://example.com")!)
        .navigationBarItems(
          trailing: Button(
            action: { },
            label: { Text("Done") }
          )
        )
      }
    }
}

import WebKit

struct WebView: UIViewRepresentable {
  let url: URL

  func makeUIView(
    context: UIViewRepresentableContext<WebView>
  ) -> WKWebView {
    return WKWebView()
  }

  func updateUIView(
    _ view: WKWebView,
    context: UIViewRepresentableContext<WebView>
  ) {
    view.load(URLRequest(url: url))
  }
}


struct Sample_Previews: PreviewProvider {
    static var previews: some View {
        Sample()
    }
}

The result here is a very weird gap (black) between the navigation bar (gray w/ done button) and the web content (white):