Firebase Firestore showing warning

Question

I am doing a project with ionic 3 and firebase firestore used as the database.

But My firebase firestore showing warning whenever I making a CRUD operation.

 index.esm.js:77 [2018-05-02T05:45:40.408Z]  @firebase/firestore: 
 Firestore (4.13.0): 
 The behavior for Date objects stored in Firestore is going to change
 AND YOUR APP MAY BREAK.
 To hide this warning and ensure your app does not break, you need to 
 add the
 following code to your app before calling any other Cloud Firestore 
 methods:

 const firestore = firebase.firestore();
 const settings = {/* your settings... */ timestampsInSnapshots: 
 true};
 firestore.settings(settings);

 With this change, timestamps stored in Cloud Firestore will be read 
 back as
 Firebase Timestamp objects instead of as system Date objects. So you 
 will also
 need to update code expecting a Date to instead expect a Timestamp. 
 For example:

 // Old:
 const date = snapshot.get('created_at');
 // New:
 const timestamp = snapshot.get('created_at');
 const date = timestamp.toDate();

 Please audit all existing usages of Date when you enable the new 
 behavior. In a
 future release, the behavior will change to the new behavior, so if 
 you do not
 follow these steps, YOUR APP MAY BREAK.

Answer 1

I added below code in app.module.ts then error correct.

firebase.initializeApp(environment.firebase) // Load firebase server settings

firebase.firestore().settings( { timestampsInSnapshots: true })