Where does this exclamation mark triangle come from?

Attaching I send you a screenshot of the Terms & Conditions popup of my site. There is an annoying exclamation mark symbol far left, of which i can't get rid of.
I'm using my own template (wfw2).

Go to url:
https://creativeflute.at/index.php?option=com_content&;view=article&id=9flegetipps-fuer-querfloeten&catid=18:werkstatt&Itemid=299

Is there any kind of error?
In the page source I find this:

<div class="o-empty__content"><i class="o-empty__icon fa fa-exclamation-triangle"></i> <div class="o-empty__text"><span class="kt-dialog-error-message"></span></div> </div>

But there is no error message.

Thank you for your help!