message: elaborate Error msg
diff: @@ -313,7 +313,7 @@ impl DomTree {
  .map(|x| {
  rmap.get(&x)
  .unwrap_or_else(|| {
  - radeco_err!("Node not found");
  + radeco_err!("DomTree.build_dom_tree: Node not found");
  &dummy
  })
  });
  