Unknown string in widget

[gabviv73]

I'm using Responsive theme, and activating tiny_coffee as a widget puts the word "coffee" between the widget title and the widget text: why ?
See screenshot:

[ideag]

Hi, @Gabrielev. Which sidebar are we talking about? I can't replicate this in the ones I've tried.

[gabviv73]

I have updated the plugin today, and the problem persists.
I use Cusotomzr template, and I have found out that the unknown string is an image.
The html source of the wrong part is:

<pre>
<h3 class="widget-title">Offrimi un caffè !</h3>
<div class="tiny_coffee tiny_coffee_widget">
<section class="modal-body" data-icon="coffee" data-price="1" data-rate="1" data-currency="€%s" data-hash="#cofffee">                                         <div class="tiny_coffee_text">
<p>Se le informazioni che hai trovato su questo sito sono state interessanti, puoi offrirmi un caffè:</p>

The hoghlighted word "coffee" is generated by the tag

data-icon="coffee"

If I change the plugin icon in the settings to "beer", I get the word "beer" displayed.
Using the theme Twenty fourteen, the wrong word is not displayed.