<ul><li><b>group.controller.php line 306 fix</b>: <code>$r["group_post_restriction"]</code> — field not present in the add/edit group form; when editing a group the JS calls <code>insertGroup()</code> which routes to <code>updateGroup()</code> but the form has no <code>group_post_restriction</code> input; <code>null</code> value passed to DB column causing <code>Data truncated for column post_restriction</code> fatal error + PHP warning → JSON.parse broke with <code>Unexpected token "<"</code>; fixed with <code>?? 1</code> default</li><li>updateGroup now returns clean JSON ✓</li></ul>