check that the argument is not empty in wxHtmlWindow::LoadPage() to avoid crashing if it is

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@53853 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/html/htmlwin.cpp

@@ -468,6 +468,8 @@ bool wxHtmlWindow::AppendToPage(const wxString& source)
 
 bool wxHtmlWindow::LoadPage(const wxString& location)
 {
+    wxCHECK_MSG( !location.empty(), false, "location must be non-empty" );
+
     wxBusyCursor busyCursor;
 
     wxFSFile *f;