tdf#120703 PVS: dereference before nullptr check

V595 The 'GetActiveWindow()' pointer was utilized before it was verified against nullptr.
     Check lines: 544, 567.

Change-Id: I1ef45fa72542168ba88f24482973a1c660bcc1a8
Reviewed-on: https://gerrit.libreoffice.org/71470
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

sd/source/ui/view/drviewsa.cxx

@@ -535,7 +535,8 @@ void DrawViewShell::GetStatusBarState(SfxItemSet& rSet)
        or page) with the help of the ZoomItems !!!   */
     if( SfxItemState::DEFAULT == rSet.GetItemState( SID_ATTR_ZOOM ) )
     {
-        if (GetDocSh()->IsUIActive() || (SlideShow::IsRunning(GetViewShellBase())) )
+        if (GetDocSh()->IsUIActive() || SlideShow::IsRunning(GetViewShellBase())
+            || !GetActiveWindow())
         {
             rSet.DisableItem( SID_ATTR_ZOOM );
         }