Fix #462 Can't delete Categories and Subcategories event handling in …

…deleteSubmit button

oc-admin/themes/modern/categories/index.php

@@ -306,7 +306,9 @@ function delete_category(id) {
  return false;
  }
 
- document.getElementById("deleteSubmit").onclick = function () {
+ document.getElementById("deleteSubmit").onclick = function (e) {
+ // prevent other events
+ e.preventDefault();
  let categoryId = document.getElementById(
  "deleteModal"
  ).dataset.categoryId;