nextcloud-server/apps/files/templates/index.php

<!-- File navigation -->
<div id="app-navigation-files" role="navigation"></div>

<!-- File list vue container -->
<div id="app-content-vue" class="hidden"></div>

<!-- config hints for javascript -->
<input type="hidden" name="filesApp" id="filesApp" value="1" />
<input type="hidden" name="fileNotFound" id="fileNotFound" value="<?php p($_['fileNotFound']); ?>" />