title: message notification error catch admin-on-rest
body: <p>I try to show in notification the error of the catch like this:</p>
  
  <pre><code>  .catch(e =&gt; {
      console.error('catch', e);
      showNotification(e, 'warning');
    });
  </code></pre>
  
  <p>This doesn't work.</p>
  
  <p>I follow the instructions on <a href="https://github.com/marmelab/admin-on-rest/blob/master/docs/Actions.md" rel="nofollow noreferrer">Actions admin-on-rest</a></p>
  
  <p>In this are examples like: </p>
  
  <pre><code>        .catch((e) =&gt; {
              console.error(e);
              showNotification('Error: comment not approved', 'warning')
          });
  </code></pre>
  
  <p>but I want to show in showNotification the <code>e</code> message.</p>
  
  <p>How can I do this?</p>