diff --git a/airlock/static/assets/file_browser/dir.js b/airlock/static/assets/file_browser/dir.js
index 3d4f8578..3a3655aa 100644
--- a/airlock/static/assets/file_browser/dir.js
+++ b/airlock/static/assets/file_browser/dir.js
@@ -1,13 +1,11 @@
-// ensure datatable is initialised when loading over HTMX
-window.initCustomTable ? window.initCustomTable() : null;
-
 // implement select all checkbox
-function toggleSelectAll(elem, event) {
+function toggleSelectAll(elem) {
     const form = document.querySelector("#multiselect_form");
 
-    const checkboxes = form.querySelectorAll('input[type="checkbox"]');
+    /** @type {NodeListOf<HTMLInputElement>|undefined} */
+    const checkboxes = form?.querySelectorAll('input[type="checkbox"]');
 
-    checkboxes.forEach(function(checkbox) {
+    checkboxes?.forEach(function(checkbox) {
         checkbox.checked = elem.checked;
     });
 }