fix: Don't log error for not finding header when running in headless mode (#3112)

internal/ui/app.go

@@ -123,11 +123,13 @@ func (a *App) StylesChanged(s *config.Styles) {
 	a.Main.SetBackgroundColor(s.BgColor())
 	if f, ok := a.Main.GetPrimitive("main").(*tview.Flex); ok {
 		f.SetBackgroundColor(s.BgColor())
+		if !a.Config.K9s.IsHeadless() {
 			if h, ok := f.ItemAt(0).(*tview.Flex); ok {
 				h.SetBackgroundColor(s.BgColor())
 			} else {
 				log.Error().Msgf("Header not found")
 			}
+		}
 	} else {
 		log.Error().Msgf("Main not found")
 	}