Update handler.js to allow access to MUTATION_OPS

This moves mutation ops to a constant outside the object. The original example will result in MUTATION_OPS not found.

Author: cloke

snippets/updating-data/create-record/handler.js

@@ -2,9 +2,10 @@
 import { recordIdentifierFor } from '@ember-data/store';
 import { serializeResources } from '@ember-data/json-api/request';
 
-const updatesHandler = {
-  MUTATION_OPS: new Set(['createRecord', 'updateRecord']),
+const MUTATION_OPS = new Set(['createRecord', 'updateRecord']);
+
 
+const updatesHandler = {
   request(context, next) {
     if (!MUTATION_OPS.has(context.request.op)) {
       // Not a mutation, do nothing