kf.windowsystem: static bool KX11Extras::compositingActive() may only be used on X11

The line in the title gets logged each time the quicksettings menu is opened/closed. Chcked with pmOS edge on op6-enchilada.

KX11Extras.compositingActive is called inside shell/contents/views/Panel.qml at L215 and L236: maybe those calls should get enclosed in a if-clause checking for X11 platform before calling that KX11Extras.compositingActive..?

Looking at the commit message in KWindowSystem that IMO is relevant for this, the following is included:

Since this changes the behavior of calling KX11Extras on non-X11 platforms add a check to warn and gracefully exit when that happens

That commit also removed the following code from src/platforms/wayland/windowsystem.cpp

bool WindowSystem::compositingActive()
{
    // wayland is always composited
    return true;
}

so IIUC checking if compositing is active is the same like checking if we are under wayland platform, then maybe it would be fine to substitute that KX11Extras::compositingActive() with keep only KWindowSystem::isPlatformWayland() in shell/contents/views/Panel.qml#L236?

Sounds simple enough that I could try to fix this myself and check the outcome...