Unity sees the error but vs doesn't?

Question

C++ / C#

Unity gives errors
"Unexpected symbol `void' in class, struct, or interface member declaration(points to void in Market method)"
"Unexpected symbol `.', expecting `)', `,', `;', `[' , or `='(points to .Launcher in the Market method)"
Visual studio quietly saves the script without underlining anything or seeing an error.
Part of the code with an error.

public void Sound_3()
  {
    gameObject.SetActive(false);
    sound_3.SetActive(true);
  }

public async void Market()
  {	
    await Windows.System.Launcher.LaunchUriAsync(new Uri("ms-windows-store:reviewapp?appid=" + Windows.ApplicationModel.Store.CurrentApp.AppId));
    }

public void Back_time()
  {
    gameObject.SetActive(false);
    main.SetActive(true);
  }

What is the jamb?

Answer 1

Most likely .Mono in the version that Unity uses does not support async. VisualStudio is not aware of this, of course. What you want to do can be done, for example, through a coroutine.