[Security Solution][Detection Engine] fixes 410 error on index legacy template call

x-pack/plugins/lists/server/routes/utils/remove_templates_if_exist.ts

@@ -8,9 +8,10 @@
 import { ListClient } from '../../services/lists/list_client';
 
 export const removeLegacyTemplatesIfExist = async (lists: ListClient): Promise<void> => {
-  const legacyTemplateExists = await lists.getLegacyListTemplateExists();
-  const legacyTemplateListItemsExists = await lists.getLegacyListItemTemplateExists();
   try {
+    const legacyTemplateExists = await lists.getLegacyListTemplateExists();
+    const legacyTemplateListItemsExists = await lists.getLegacyListItemTemplateExists();
+
     // Check if the old legacy lists and items template exists and remove it
     if (legacyTemplateExists) {
       await lists.deleteLegacyListTemplate();
@@ -19,7 +20,8 @@ export const removeLegacyTemplatesIfExist = async (lists: ListClient): Promise<v
       await lists.deleteLegacyListItemTemplate();
     }
   } catch (err) {
-    if (err.statusCode !== 404) {
+    // 410 error is for ES serverless, this API doesn't exist there any more, so _template request returns 410 error
+    if (err.statusCode !== 404 && err.statusCode !== 410) {
       throw err;
     }
   }