Warning when org.gnome.desktop.wm.preferences.button-layout is empty on either side

[TheNullicorn]

When org.gnome.desktop.wm.preferences.button-layout has nothing on either side of the :, this warning gets logged.

These lines in get_button_layout_config produce the empty halves, and then this split in parse_button_layout_side doesn't catch them so the warning winds up being

Ignoring unknown button type: 

Ubuntu 24.04's default button-layout triggers this (:minimize,maximize,close). For me that dbus-send command returns:

   variant       variant          :minimize,maximize,close

Details
OS: Ubuntu 24.04
WM: Wayland
sctk-adwaita: 0.9.0 (<-- transitively from winit 0.30.1 <-- bevy 0.14.0)