Atom feed contains non valid xhtml summary when emoji is used.
When using an emoji in a comment the atom feed renders the following fragment:
...
<entry>
...
<summary type="xhtml">
<div xmlns='http://www.w3.org/1999/xhtml'>
<p>Some text.</p>
<ul>
<li>Item one</li>
<li>Item two</li>
</ul>
<p>Text with <a href="http://www.google.com">link</a> and emoji: <img class="emoji" title=":-1:" alt=":-1:" src="https://gitlab.com/assets/emoji/-1-2738e8a8e7556d395e51bee346090f16.png" height="20" width="20"> </p>
</div>
</summary>
</entry>
...
Because the img-Tag is not closed fedd readers aren't able to parse the complete feed.