fix(handle-callback): fix assinging values to firestore doc object

Author: leomp12

lib/methods/handle-callback.js

@@ -29,7 +29,7 @@ const handleCallback = client => {
           }
         : null
       if (collRef && application) {
-        Object.assign(application, {
+        Object.assign(firestoreDoc, {
           application_id: application._id,
           application_app_id: application.app_id,
           application_title: application.title
@@ -44,7 +44,7 @@ const handleCallback = client => {
         // insert application with respective authentication data
         if (collRef) {
           const { Timestamp } = require('firebase-admin').firestore
-          Object.assign(application, {
+          Object.assign(firestoreDoc, {
             authentication_permissions: JSON.stringify(authentication.permissions),
             created_at: Timestamp.now(),
             updated_at: new Timestamp(1500000000, 0) // Jul 13 2017
@@ -75,7 +75,7 @@ const handleCallback = client => {
         // authentication flux callback
         // should update access token for current authentication
         if (collRef) {
-          Object.assign(application, {
+          Object.assign(firestoreDoc, {
             access_token: reqBody.access_token,
             expires: reqBody.expires,
             updated_at: require('firebase-admin').firestore.Timestamp.now()