Property 'user' does not exist on type 'Object' in Typescript and Angular 10

I know this might be a simple question but I did extensive research on how to solve it and found a good amount of resources, but for some reasons and after applying every single solution, I don't seem to get it to work and get the following error from the same function onLoginSubmit() present in the login.component.ts:

The error:

Property 'user' does not exist on type 'Object'

Property 'token' does not exist on type 'Object'

Below the most important part of the code

login.component.html

<h2 class="page-header">Login</h2>
<form (submit)="onLoginSubmit()">
  <div class="form-group">
    <label>Username</label>
    <input type="text" class="form-control" [(ngModel)]="username" name="username">
  </div>
  <div class="form-group">
    <label>Password</label>
    <input type="password" class="form-control" [(ngModel)]="password" name="password">
  </div>
  <input type="submit" class="btn btn-primary" value="Login">
</form>

login.component.ts

import { Component, OnInit } from '@angular/core';
import { AuthService } from '../../services/auth.service';
import { Router } from '@angular/router';
import { FlashMessagesService } from 'angular2-flash-messages';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.css']
})


export class LoginComponent implements OnInit {
  username!: String;
  password!: String;
  dataRegister: any={};

  constructor(private authService: AuthService,
              private router: Router,
              private flashMessagesService: FlashMessagesService) { }

  ngOnInit(): void {
  }


  onLoginSubmit() {
    const user = {
      username: this.username,
      password: this.password
    }
    this.authService.authenticateUser(user).subscribe(data => {
      this.dataRegister = data;
      console.log(this.dataRegister);
      if(this.dataRegister.success) {
        this.authService.storeUserData(data.token, data.user); // <-- Error here
        this.flashMessagesService.show('User Authenticated', {cssClass: 'alert-success', timeout: 3000});
        this.router.navigate(['dashboard']);
      } else {
        this.flashMessagesService.show('User Not Authenticated', {cssClass: 'alert-danger', timeout: 5000});
        this.router.navigate(['login']);
      }
    })
  }
  }

the function storeUserData{} is the one that is showing this type of error. Below is the file that has that function:

auth.service.ts

import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { map } from 'rxjs/operators';
import { tokenNotExpired } from 'angular2-jwt';


@Injectable({
  providedIn: 'root'
})
export class AuthService {
  authToken: any;
  user: any;

  constructor(private httpClient: HttpClient) { }
  registerUser(user) {
    const httpOptions = {
      headers: new HttpHeaders({
        'Content-Type':  'application/json',
      })
    };
    return this.httpClient.post('http://localhost:3000/users/register', user, httpOptions);
  }

  authenticateUser(user) {
    const httpOptions = {
      headers: new HttpHeaders({
        'Content-Type':  'application/json',
      })
    };
    return this.httpClient.post('http://localhost:3000/users/authenticate', user, httpOptions);
  }

  getProfile() {
    const httpOptions = {
      headers: new HttpHeaders({
        'Content-Type':  'application/json',
        Authorization: this.authToken,
      })
    };
    this.loadToken();
    return this.httpClient.get('http://localhost:3000/users/profile', httpOptions);
  }

  storeUserData(token, user) {
    localStorage.setItem('id_token', token);
    localStorage.setItem('user', JSON.stringify(user));
    this.authToken = token;
    this.user = user;
  }

  loadToken() {
    const token = localStorage.getItem('id_token');
    this.authToken = token;
  }

  loggedIn() {
    return tokenNotExpired();
  }

  logout() {
    this.authToken = null;
    this.user = null;
    localStorage.clear();
  }
}

As I mentioned above, I did a lot of research on how to solve the problem and I applied 1) this solution but didn't work and the error is still there. I also tried 2) this post but no luck with that. I went ahead and used 3) this solution and also tried 4) this one too but also did not work. After much more research I went on the Angular documentation to see if I was missing something but I don't seem to be missing anything to cause an error like this.

In addition to all the solution I tried I changed the onLoginSubmit() function I have on the login.component.ts with the one below as an additional way of solving the problem but the error is still there:

  onLoginSubmit() {
    const user = {
      username: this.username,
      password: this.password,
    }

    this.authService.authenticateUser(user).subscribe(response => {
      console.log(data);
      if('token' in response) {
        // response is SuccessResponse
        this.authService.storeUserData(response.token, response.user);
        this.flashMessagesService.show('You are logged in', {
          cssClass: 'alert-success',
          timeout: 5000});
        this.router.navigate(['dashboard']);
      } else {
        // response is FailureResponse
        this.flashMessagesService.show(response.msg, {
          cssClass: 'alert-danger',
          timeout: 5000});
        this.router.navigate(['login']);
      }
    }
  }

I am running out of ideas. Please guide to the solution or at least point to it.