TypeError: _this.setCurrentUserName is not a function but works when refresh

Question

I am using angular 7 and I have implement within the Auth service Login method a call to a method os the same service to set a variable of such method:

export class AuthService {

  private url:string = 'http://localhost:8080/Auth';

  private token:string;
  private expiresAt: number;

  private CurrentUsername : string = null;
  private currentUserId : number = null;
  public CurrentUserroles : RoleModelDTO[];

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

  login(loginModel : LoginModelDTO){

    const headers = new HttpHeaders(
      {
        'Content-Type': 'application/json'
      }
    );

    this.http.post(`${this.url}/login`,loginModel,{headers}).subscribe( 
      (resp: LogedUserModelDTO) => {
        console.log(resp);
        this.setToken(resp.token);
        this.setExpiresAt(resp.expire);
        this.setCurrentUserName(resp.username);
        this.setCurrentUserId(resp.userId);
        this.setCurrentUserroles(resp.roles);
        this.router.navigate(['/MyAPP/profile', resp.userId]);
      },
      (error: HttpErrorResponse) => {
        console.log(error);
        Swal.close();
        this.handelError(error,'login Error');
      }
    );

  logout(){
    this.token = null;
    this.expiresAt = null;
    this.setCurrentUserroles = null;
    this.setCurrentUserName = null;
    this.setCurrentUserId = null;
    localStorage.clear();
    this.router.navigateByUrl('/login');
  }
  }

  getRoles(){

    let token : string = this.getToken();
    const headers = new HttpHeaders(
      {
        'Content-Type': 'application/json',
        'Authorization': `Bearer ${token}`
      }
    );

    return this.http.get(`${this.url}/getRoles`,{headers} )
  }

  private setToken(token : string){
    this.token = token;
  }

  getToken() : string{
    return this.token;
  }

  private setExpiresAt(expire:number){
    this.expiresAt = (expire * 1000) + Date.now();
  }

  setCurrentUserName(username : string){
    this.CurrentUsername = username;
  }

  getCurrentUserName() : string{
    return this.CurrentUsername
  }

  setCurrentUserId(userId : number){
    this.currentUserId = userId;
  }

  getCurrentUserId() : number{
    return this.currentUserId;
  }

  setCurrentUserroles(CurrentUserroles : RoleModelDTO[]){
    this.CurrentUserroles = CurrentUserroles;
  }

  getCurrentUserroles() : RoleModelDTO[] {
    return this.CurrentUserroles;
  }
}

(I have not included all code of the service because its so big)

As you can see, when login, there is a method: this.setCurrentUserName(resp.username);

the first time I try to log in everuthing works fine: But then if I logout anfd try to login again i get this error:

When I press F5 and reload the page it works fine again.

I dont understand why reloading the page it works and what I a doing wrong when it is just a simple method in the same service.

Thank you!

IMPORTANT

I Know i can just do this: this.CurrentUsername = resp.username; this.currentUserId = resp.userId;

and so on, but i dont want to do this because this methods were first in another service with the same error and I want to know what produces it