deskbar: Fix PVS V757

Use dynamic_cast to menuItem after NULL checking to it.

Change-Id: I3fdabf5a091922587f498cf5fa116f8824bbfc6b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2160
Reviewed-by: Adrien Destugues <[email protected]>
Reviewed-by: Jérôme Duval <[email protected]>

src/apps/deskbar/ExpandoMenuBar.cpp

@@ -351,8 +351,6 @@ TExpandoMenuBar::MouseMoved(BPoint where, uint32 code, const BMessage* message)
 			{
 				BMenuItem* menuItem;
 				TTeamMenuItem* item = TeamItemAtPoint(where, &menuItem);
-				TWindowMenuItem* windowMenuItem
-					= dynamic_cast<TWindowMenuItem*>(menuItem);
 
 				if (item == NULL || menuItem == NULL) {
 					// item is NULL, remove the tooltip and break out
@@ -366,6 +364,9 @@ TExpandoMenuBar::MouseMoved(BPoint where, uint32 code, const BMessage* message)
 					break;
 				}
 
+				TWindowMenuItem* windowMenuItem
+					= dynamic_cast<TWindowMenuItem*>(menuItem);
+
 				if (windowMenuItem != NULL && fBarView->Vertical()
 					&& fBarView->ExpandoState() && item->IsExpanded()) {
 					// expando mode window menu item