bugfix: generating new account failed due to null webhook_secret

lib/routes/api/accounts.js

@@ -291,7 +291,7 @@ router.post('/', async(req, res) => {
     await validateAdd(req);
 
     // create webhooks if provided
-    const obj = Object.assign({webhook_secret: secret}, req.body);
+    const obj = {...req.body, webhook_secret: secret};
     for (const prop of ['registration_hook']) {
       if (obj[prop]) {
         obj[`${prop}_sid`] = await Webhook.make(obj[prop]);