calling insert("") would provoke an assert - now it's just ignored

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@622 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/string.cpp

@@ -930,6 +930,7 @@ wxString& wxString::insert(size_t nPos, const wxString& str)
   wxASSERT( str.GetStringData()->IsValid() );
   wxASSERT( nPos <= Len() );
 
+  if ( !str.IsEmpty() ) {
     wxString strTmp;
     char *pc = strTmp.GetWriteBuf(Len() + str.Len());
     strncpy(pc, c_str(), nPos);
@@ -937,6 +938,7 @@ wxString& wxString::insert(size_t nPos, const wxString& str)
     strcpy(pc + nPos + str.Len(), c_str() + nPos);
     strTmp.UngetWriteBuf();
     *this = strTmp;
+  }
 
   return *this;
 }