tdf#125397: Avoid crash if GetpApp() returns null, can happen on iOS at least

Change-Id: Ib0dfb00c6a00640fe35769f21f167bf3eae8769b
diff --git a/vcl/source/window/window.cxx b/vcl/source/window/window.cxx
index 7435ce1..c6dc064 100644
--- a/vcl/source/window/window.cxx
+++ b/vcl/source/window/window.cxx
@@ -2299,7 +2299,9 @@ void Window::Show(bool bVisible, ShowFlags nFlags)
            if ( !pSVData->mpIntroWindow )
            {
                // The right way would be just to call this (not even in the 'if')
                GetpApp()->InitFinished();
                auto pApp = GetpApp();
                if ( pApp )
                    pApp->InitFinished();
            }
            else if ( !ImplIsWindowOrChild( pSVData->mpIntroWindow ) )
            {