title: jh_captcha throws "Validation failed while trying to call showAction"
body: <p>I've implemented jh_captcha into my extension as descripted in the documentation:</p>
  
  <p><a href="https://docs.typo3.org/typo3cms/extensions/jh_captcha/Developer/Index.html#add-the-captcha-to-your-domain-model" rel="nofollow noreferrer">https://docs.typo3.org/typo3cms/extensions/jh_captcha/Developer/Index.html#add-the-captcha-to-your-domain-model</a></p>
  
  <p>It's working create within Actions like New, Edit or List. But I get the following error as soon <code>showAction</code> is called:</p>
  
  <pre><code>Validation failed while trying to call showAction
  </code></pre>
  
  <p>As soon as I remove <code>NotEmpty</code> from the validation the showActions are working, but New and Edit obviously not.</p>