Display at least the title when there is no custom filters

app/Template/custom_filter/index.php

@@ -1,4 +1,3 @@
-<?php if (! empty($custom_filters)): ?>
 <div class="page-header">
     <h2><?= t('Custom filters') ?></h2>
     <ul>
@@ -7,6 +6,7 @@
         </li>
     </ul>
 </div>
+<?php if (! empty($custom_filters)): ?>
     <table class="table-striped table-scrolling">
         <tr>
             <th class="column-15"><?= t('Name') ?></th>
@@ -49,5 +49,7 @@
         </tr>
     <?php endforeach ?>
     </table>
+<?php else: ?>
+    <p class="alert"><?= t('There is no custom filter.') ?></p>
 <?php endif ?>