HTML tag cause invalid acknowledgements section

[CecSve]

Feedback for #2473.

The following text with HTML tags that are supported gives an Acknowledgements is invalid. although it seems to render in the text view.

Lorem Ipsum <div>I am a div</div> dolor sit amet. 

<p>This text contains <sub>subscript</sub> text.</p>

 <p>This text contains <sup>superscript</sup> text.</p> 

 <pre>Text in a pre element
is displayed in a fixed-width
font, and it preserves
both      spaces and
line breaks</pre>

<div class="myDiv">
  <h1>This is a heading in a div element</h1>
  <p>This is some text in a div element.</p>
</div>

<a href="https://www.gbif.org">Visit gbif.org!</a> 
<p>This is normal text - <b>and this is bold text</b>.</p>

[mike-podolskiy90]

Thanks Cecilie.

I'm looking into improving error messages, that might help here.