qmlui: reset also the current Function editor when closing the right panel
qmlui: reset also the current Function editor when closing the right panel

Resolves a nasty crash when, for example, a Chaser has been previewed and then a new project is loaded

mcallegari/qlcplus,kripton/qlcplus,nedmech/qlcplus,sbenejam/qlcplus,sbenejam/qlcplus,sbenejam/qlcplus,nedmech/qlcplus,kripton/qlcplus,nedmech/qlcplus,plugz/qlcplus,sbenejam/qlcplus,mcallegari/qlcplus,mcallegari/qlcplus,nedmech/qlcplus,nedmech/qlcplus,plugz/qlcplus,kripton/qlcplus,kripton/qlcplus,plugz/qlcplus,mcallegari/qlcplus,plugz/qlcplus,nedmech/qlcplus,kripton/qlcplus,mcallegari/qlcplus,sbenejam/qlcplus,kripton/qlcplus,plugz/qlcplus,mcallegari/qlcplus,plugz/qlcplus,sbenejam/qlcplus,mcallegari/qlcplus,kripton/qlcplus,plugz/qlcplus,sbenejam/qlcplus