XML : Not well-formed XML error using Firefox and jQuery .children()

I am facing a bug I am not able to resolve.

To repoduce it, launch Firefox, then go on the jQuery's home page, open the javascript console and execute the following code:

  var xml =   `<?xml version="1.0" encoding="UTF-8"?>  <root>    <value>      <string>Test</string>    </value>  </root>`    var $xml = $.parseXML(xml);  var $root = $($xml).children("root");  console.log($root);    

For no reason, $root is ok but it raises a not well-formed error in the console.

I know this is because of .children("root") but I do not find a way to fix it. There is no error using Chrome.

Could someone explain me why do I get this message, and how to prevent this error, please?