Letters disappear, ins tag not closed

[karabijavad]

$a = new HtmlDiff('<p>1.1', 'test');
echo $a->build();

outputs:

<ins class='mod'><del class="diffmod">.1</del><ins class="diffmod">test</ins>

<p>1 is not shown as being removed, and the opening <ins class='mod'> tag is not closed.