prevent non empty category removal

application/Espo/Resources/i18n/en_US/Global.json

@@ -415,7 +415,9 @@
         "select2OrMoreRecords": "Select 2 or more records",
         "selectNotMoreThanNumberRecords": "Select not more than {number} records",
         "selectAtLeastOneRecord": "Select at least one record",
-        "duplicateConflict": "A record already exists."
+        "duplicateConflict": "A record already exists.",
+        "cannotRemoveCategoryWithChildCategory": "Cannot remove a category that has a child category.",
+        "cannotRemoveNotEmptyCategory": "Cannot remove a non-empty category."
     },
     "boolFilters": {
         "onlyMy": "Only My",

application/Espo/Services/RecordTree.php

@@ -313,6 +313,33 @@ class RecordTree extends Record
         }
     }
 
+    /**
+     * @throws Forbidden
+     * @throws BadRequest
+     */
+    protected function beforeDeleteEntity(Entity $entity)
+    {
+        parent::beforeDeleteEntity($entity);
+
+        $childCategory = $this->entityManager
+            ->getRelation($entity, 'children')
+            ->findOne();
+
+        if ($childCategory) {
+            throw Forbidden::createWithBody(
+                'cannotRemoveCategoryWithChildCategory',
+                Error\Body::create()->withMessageTranslation('cannotRemoveCategoryWithChildCategory')
+            );
+        }
+
+        if (!$this->checkItemIsEmpty($entity)) {
+            throw Forbidden::createWithBody(
+                'cannotRemoveNotEmptyCategory',
+                Error\Body::create()->withMessageTranslation('cannotRemoveNotEmptyCategory')
+            );
+        }
+    }
+
     public function update(string $id, stdClass $data, UpdateParams $params): Entity
     {
         if (!empty($data->parentId) && $data->parentId === $id) {