app PostFunc is not called because of screen being nil while calling PostFunc [race condition]

[Viv1k]

I created a simple app with a window having three texts. I want to call function PostFunc and set their text to something else. But I think PostFunc does not work because of following race condition.

app := &views.Application{}
     app.SetStyle(tcell.StyleDefault.
         Foreground(tcell.ColorWhite).
         Background(tcell.ColorBlack))
     app.SetRootWidget(window)
     app.Start()
     // time.Sleep(1 * time.Second)
     app.PostFunc(setContent)
     if e := app.Wait(); e != nil {
         fmt.Fprintln(os.Stderr, e.Error())
         os.Exit(1)

app.Starts() starts run function in a go routine and creates a screen if some screen is not set.
During the time when called app.Start() called and new screen is not initialize. PostFunc would return saying screen is nil.
Following is PostFunc code:

// PostFunc posts a function to be executed in the context of the
 // application's event loop.  Functions that need to update displayed
 // state, etc. can do this to avoid holding locks.
 func (app *Application) PostFunc(fn func()) {
     ev := &eventAppFunc{fn: fn}
     ev.SetEventNow()
     if scr := app.screen; scr != nil { // Code returns from here
         go func() { scr.PostEventWait(ev) }()
     }
 }

[gdamore]

This is a bug in the views sub package, not in tcell itself.