"Argument of type 'string | undefined' is not assignable to parameter of type 'string'" for user.token

I am working on a project using ASP.NET Core Web API and Angular 13.

The login post request from the endpoint is:

> https://localhost:44396/api/v1/auth/login

    {
       "status_code": 200,
       "message": "Successfully Logged In",
       "result": {
           "token": "gggggffffffffffffdddddddddddd",
           "user": {
               "id": 3,
               "user_name": "smith",
               "last_login": "2022-01-03T12:35:26.0305649"
              },
           "roles": [
               "Teacher"
           ],
           "expires": "2022-01-03T14:40:33Z"
       }
    }

This is the Angular code:

user.ts:

export interface IResponse<T> {
  message: string;
  error: boolean;
  code: number;
  results: T;
}

export interface IUser {
  userName?: string;
  lastLogin?: Date;
  token?: string;
  roles?: string[];
  expires?: Date;
}

auth.service.ts:

export class AuthService {
  baseUrl = environment.apiUrl;
  private currentUserSource = new ReplaySubject<IUser>(1);
  currentUser$ = this.currentUserSource.asObservable();

  constructor(private http: HttpClient, private router: Router) { }

  login(model: any){
    return this.http.post(this.baseUrl+'auth/login', model).pipe(
      map((res: IUser)=>{
        const user = res;
        if(user){
          this.setCurrentUser(user);
        }
      })
    )
  }

  setCurrentUser(user: IUser){
    if(user){
      user.roles = [];
      const roles = this.getDecodedToken(user.token).role;//copy token to jwt.io see .role
      Array.isArray(roles) ? user.roles = roles : user.roles.push(roles);
      localStorage.setItem('user', JSON.stringify(user));
      this.currentUserSource.next(user);
    }
  }

  getDecodedToken(token: string) {
    return JSON.parse(atob(token.split('.')[1]));
  }
}

I got this error:

error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.

With this code highlighted in setCurrentUser: user.token

How do I resolve it?

>Solution :

Please try

const roles = this.getDecodedToken(user.token || '').role;