Event plugin pages html is not valid

[WhiteWolfSix]

There are few code errors that leads to various issues when trying to validate event page. Here are some of them in events.html.twig
An img element must have an alt attribute, except under certain conditions.

          <div class="featured-event-masthead">
            {% set image = event.media.images|first %}
            {% if image != null %}
              {{ image.cropZoom(1200,400).html }}
            {% endif %}
            <h3 class="featured-event-title"><a href="{{ event.url }}">{{ event.title }}</a></h3>
          </div>

Self-closing syntax (/>) used on a non-void HTML element. Ignoring the slash and treating as a start tag.
<a href="{{ event.url }}" class="event-button" />{{ 'PLUGIN_EVENTS.EVENTS.BUTTON'|t }}</a>

Section lacks heading. Consider using h2-h6 elements to
<section class="featured-events">

I only tried validate page created by events.html.twig, haven't validate other pages.