given an assert when trying to do something stupid

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_4_BRANCH@17531 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

contrib/src/xrc/xmlres.cpp

@@ -895,6 +895,8 @@ wxIcon wxXmlResourceHandler::GetIcon(const wxString& param,
 
 wxXmlNode *wxXmlResourceHandler::GetParamNode(const wxString& param)
 {
+    wxCHECK_MSG(m_node, NULL, wxT("You can't access handler data before it was initialized!"));
+
     wxXmlNode *n = m_node->GetChildren();
 
     while (n)