anchor.diff:    <% if doc.children.length > 0 %>
       <% if node_type(doc.node_type) == :element %>
         <span class="markup">&gt;</span></div>
  -      <% if error_id %>
  +      <% if error_id && errors && errors.count > 0%>
           <% popup_title, popup_button_text, popup_content = popup_attributes(errors) %>
           <% # button to display popup with error message(s) %>
           <% btn_errors = '' %>
  
positive.code:   <% when :element %>
      <% prefix = doc.namespace.nil? ? "" : (doc.namespace.prefix || "") %>
      <% doc_name = prefix == "" ? doc.name : "#{prefix}:#{doc.name}" %>
      <div <%=  error_id ? "class='error'".html_safe : '' %> >
      <span class="markup">&lt;</span>
      <span class="start-tag "><%= doc_name %></span>
      <% doc.namespace_definitions.each do |ns| %>
  
negative.code: #   execution_errors
  
  %>
  <% return if doc.nil? %>
  
  <% error_id = (doc['error_id']) %>
  <div <%=  error_id ? %{id=xerror_#{error_id}} : '' %> class="indent ">
    <% if error_id %>
      <% # create error message to be displayed in popup %>
  