Here is a boiled down snipped; basically its the mechanism from the flappybird demo(which does not throw that message). if I take out the assignment of visible and enabled, it works, but then I get other clashes with conflicting scenes in my project.
import Felgo 3.0
import QtQuick 2.0
property alias window: window
////// // NOTE: in qt5, an opaque element is not invisible by default and would handle the mouse and keyboard input!
////// // thus to disable also keyboard focus and mouse handling and make an item invisible, set visible and enabled property depending on opacity
visible: opacity === 0 ? false : true
// show the splash and start the loading process as soon as the GameWindow is ready