title: Display an error message in a RenderTable Rshiny
body: <p>I would like to display an error message in my shiny app if it's impossible to build the table (because of the selected criteria) :</p>
  <pre><code>output$tableau_taux &lt;- renderTable({
      tab_taux &lt;- NULL
      tab_taux &lt;- tableau_taux_fonction(input$etab_id,input$pcs_id,input$retard_id,input$sexe_id)
      validate(
        need(!is.null(tab_taux), &quot;Veuillez sélectionner d'autres critères&quot;)
      )
      tab_taux  
  })
  </code></pre>
  <p>This doesn't work, if the table is impossible to build then the R error message is displayed instead of the desired one :</p>
  <blockquote>
  <p><strong>Error : Problem with <code>filter()</code> input <code>..1</code>.
  [34mi[39m Input <code>..1</code> is <code>&amp;...</code>.
  [31mx[39m Input <code>..1</code> must be of size 741 or 1, not size 0.</strong></p>
  </blockquote>