SwiftUI web view doesn’t show up the first time – Blancer.com Tutorials and projects

I’d like to use webview with html and javascript to render something. Below is the complete code to reproduce the problem. I expect TestViewPreview to first render text “hello testview”, and after 5 seconds it renders “hello2 testview”. However, only the 2nd one is rendered. For the first one it gives some error not sure if related:

evaluateJavaScript: render(‘hello testview’); TestView.updateUIView
error: Error Domain=WKErrorDomain Code=4 “A JavaScript exception
occurred” UserInfo={WKJavaScriptExceptionLineNumber=0,
WKJavaScriptExceptionMessage=TypeError: undefined is not a function,
WKJavaScriptExceptionColumnNumber=0, NSLocalizedDescription=A
JavaScript exception occurred}

Could you please take a look at the code below?

struct MyState {
  var text: String = "abc"
}

struct TestView: UIViewRepresentable {
  let htmlPath: String
  @Binding var state: MyState
  
  func makeUIView(context: Context) -> WKWebView {
    if let htmlPath = Bundle.main.path(forResource: htmlPath, ofType: "html") {
      do {
        let htmlString = try String(contentsOfFile: htmlPath)
        WebViewHelper.webView.loadHTMLString(htmlString, baseURL: Bundle.main.bundleURL)
        WebViewHelper.webView.scrollView.showsHorizontalScrollIndicator = true
        print("TestView.makeUIView: Finished inital loading.")
      } catch {
        print("TestView.makeUIView: Error loading HTML file: (error)")
      }
    }
    return WebViewHelper.webView
  }
  
  func updateUIView(_ webView: WKWebView, context: Context) {
    let script = "render('(state.text)');"
    print("evaluateJavaScript: (script)")
    webView.evaluateJavaScript(script) { _, error in
      if let error = error {
        print("TestView.updateUIView error: (error)")
      }
    }
  }
}

struct TestViewPreview: View {
  @State private var state = MyState(text: "hello testview")
  
  var body: some View {
    TestView(htmlPath: "test_html", state: self.$state)
      .onAppear {
        DispatchQueue.main.asyncAfter(deadline: .now() + 5.0) {
          state.text = "hello2 testview"
        }
      }
  }
}

#Preview {
  TestViewPreview()
}

test_html.html

<!DOCTYPE html>
<head>
  <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
  <div id="output"></div>
  <script>
    function render(text) {
      document.getElementById("output").innerHTML = text
    }
  </script>
</body>
</html>