Merge pull request #5361 from atm-alexis/FIX_develop_Link_no_inclusion

FIX a task without project inclusion call a non included object Link

htdocs/core/lib/project.lib.php

@@ -162,6 +162,7 @@ function task_prepare_head($object)
 	$head[$h][0] = DOL_URL_ROOT.'/projet/tasks/document.php?id='.$object->id.(GETPOST('withproject')?'&withproject=1':'');
 	$filesdir = $conf->projet->dir_output . "/" . dol_sanitizeFileName($object->project->ref) . '/' .dol_sanitizeFileName($object->ref);
 	include_once DOL_DOCUMENT_ROOT.'/core/lib/files.lib.php';
+	include_once DOL_DOCUMENT_ROOT.'/core/class/link.class.php';
 	$nbFiles = count(dol_dir_list($filesdir,'files',0,'','(\.meta|_preview\.png)$'));
     $nbLinks=Link::count($db, $object->element, $object->id);
 	$head[$h][1] = $langs->trans('Documents');