Unable to render XML in correct order using highlight.js

I am trying to highlight the XML using highlight.js.

Here is the example codepen link

But I am facing two problems:

1. the self closing elements are rendered as non-self closing tag, author element in above example.
2. XML encoding attribute is also not getting rendered.

I have tried implementing escape method for replacing "/>" with /> but it is not working in expected way.

Example : Expected XML

<?xml version="1.0"?>
<catalog>
  <book id="bk112">
     <author id="1"/>
     <title>Visual Studio 7: A Comprehensive Guide</title>         
  </book>
</catalog>

Actual XML

  <catalog>
   <book id="bk112">
     <author id="1">
     <title>Visual Studio 7: A Comprehensive Guide</title>       
    </author>
   </book>
  </catalog>

Is there a way to correct this behaviour.

In this case, code tag gets parsed the HTML. to avoid you can use textarea

(function() {
  var el = document.querySelector(".xml"),
    pre = document.querySelector("pre");

  pre.innerText = el.value;
  hljs.highlightBlock(pre);
})();

<script src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/highlight.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/styles/vs.min.css" rel="stylesheet"/>

<div hidden>
  <textarea class="xml">
    <?xml version="1.0"?>
    <catalog>
      <book id="bk112">
         <author id="1"/>
         <title>Visual Studio 7: A Comprehensive Guide</title>

      </book>
    </catalog>
  </textarea>
</div>

<pre></pre>