title: Failing in liquid include if parameter not set
body: <p>Let's say I have an include snippet <code>foo.html</code> like so:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;a href="table/{{include.file}}.html"&gt;
      &lt;img src="{{include.file}}.svg" alt="{{ include.alt | default: 'Figure' }}"&gt;
  &lt;/a&gt;
  </code></pre>
  
  <p>This should be called like:</p>
  
  <pre><code>{% include foo.html file="blah" %}
  </code></pre>
  
  <p>I'd like to fail the liquid run with a diagnostic if the <code>file="blah"</code> part is missing (there is no useful default to use).</p>