arsd.dom appenChild method gives assertion message

Sun Dec 11 09:52:29 PST 2016

I would like to add first documents content inside a div element 
like this.

import arsd.dom;
import std.stdio;

void main()
{

    auto document = new Document();

    document.parseGarbage(`<html>
      <head>
      <title>Test Document1</title>
      </head>
      <body>
      <p>This is the first paragraph of our <a 
href="test.html">test document</a>.
      <p>This second paragraph also has a <a 
href="test2.html">link</a>.
      <p id="custom-paragraph">Old text</p>
      </body>
      </html>`);

    auto document2 =  new Document();

    document2.parseGarbage(`<html>
      <head>
      <title>Test Document</title>
      </head>
      <body>
      <div id="foo"></div>
      <a href="www.example.com"></a>
      <div id="content">
      </div>
      <p id="custom-paragraph">Old text</p>
      </body>
      </html>`);

    Element content = 
document2.getElementsBySelector(`div[id="content"]`)[0];

    writeln(content);

    Element[] firstElements = 
document.getElementsBySelector("body");
    writeln (firstElements);

    content.appendChild(firstElements[0]);
}

The program compiles fine. But when I try to execute it gives an 
assertion error like this.

??:? _d_assert_msg [0x80cc048]
??:? 
_D4arsd3dom7Element11appendChildMFC4arsd3dom7ElementZ9__requireMFZv [0x80a6f62]
??:? arsd.dom.Element 
arsd.dom.Element.appendChild(arsd.dom.Element) [0x80a6df1]
??:? _Dmain [0x809f73c]
??:? 
_D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv 
[0x80cd792]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).tryExec(scope void delegate()) [0x80cd6dc]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).runAll() [0x80cd74e]
??:? void rt.dmain2._d_run_main(int, char**, extern (C) int 
function(char[][])*).tryExec(scope void delegate()) [0x80cd6dc]
??:? _d_run_main [0x80cd66e]
??:? main [0x809fc93]
??:? __libc_start_main [0x129532]

How should one use appendChild or similiar methods of arsd.dom 
library?