Fixed undefined action linkback variable (#28043)

htdocs/comm/action/document.php

@@ -149,7 +149,7 @@ if ($object->id > 0) {
 	print dol_get_fiche_head($head, 'documents', $langs->trans("Action"), -1, 'action');
 
 	// Link to other agenda views
-	$linkback .= '<a href="'.DOL_URL_ROOT.'/comm/action/list.php?mode=show_list&restore_lastsearch_values=1">';
+	$linkback = '<a href="'.DOL_URL_ROOT.'/comm/action/list.php?mode=show_list&restore_lastsearch_values=1">';
 	$linkback .= img_picto($langs->trans("BackToList"), 'object_calendarlist', 'class="pictoactionview pictofixedwidth"');
 	$linkback .= '<span class="hideonsmartphone">'.$langs->trans("BackToList").'</span>';
 	$linkback .= '</a>';

htdocs/comm/action/info.php

@@ -73,7 +73,7 @@ $head = actions_prepare_head($object);
 print dol_get_fiche_head($head, 'info', $langs->trans("Action"), -1, 'action');
 
 // Link to other agenda views
-$linkback .= '<a href="'.DOL_URL_ROOT.'/comm/action/list.php?mode=show_list&restore_lastsearch_values=1">';
+$linkback = '<a href="'.DOL_URL_ROOT.'/comm/action/list.php?mode=show_list&restore_lastsearch_values=1">';
 $linkback .= img_picto($langs->trans("BackToList"), 'object_calendarlist', 'class="pictoactionview pictofixedwidth"');
 $linkback .= '<span class="hideonsmartphone">'.$langs->trans("BackToList").'</span>';
 $linkback .= '</a>';

htdocs/resource/element_resource.php

@@ -333,7 +333,7 @@ if (!$ret) {
 
 			print dol_get_fiche_head($head, 'resources', $langs->trans("Action"), -1, 'action');
 
-			$linkback .= '<a href="'.DOL_URL_ROOT.'/comm/action/list.php?mode=show_list&restore_lastsearch_values=1">';
+			$linkback = '<a href="'.DOL_URL_ROOT.'/comm/action/list.php?mode=show_list&restore_lastsearch_values=1">';
 			$linkback .= img_picto($langs->trans("BackToList"), 'object_calendarlist', 'class="pictoactionview pictofixedwidth"');
 			$linkback .= '<span class="hideonsmartphone">'.$langs->trans("BackToList").'</span>';
 			$linkback .= '</a>';