don't crash in case of incorrectly specified parent type of MDI child frame (coverity checker CID 16)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@37890 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/xrc/xh_mdi.cpp

@@ -78,7 +78,10 @@ wxWindow *wxMdiXmlHandler::CreateFrame()
         wxMDIParentFrame *mdiParent = wxDynamicCast(m_parent, wxMDIParentFrame);
 
         if ( !mdiParent )
-            wxLogError(wxT("Parent is not of type wxMDIParentFrame."));
+        {
+            wxLogError(wxT("Parent of wxMDIParentFrame must be wxMDIParentFrame."));
+            return NULL;
+        }
 
         XRC_MAKE_INSTANCE(frame, wxMDIChildFrame);