I don’t see any errors in my Angular code, but when I use the developer tools, the username doesn’t appear due to text interpolation errors

I don’t see any errors in my Angular code, but when I use the developer tools, the username doesn’t appear due to text interpolation errors.you know the answer?

authservice.ts

 public get useraccountValue(): Useraccount{
return this.useraccountSubject.value; }

Useraccount.ts

export class Useraccount{

id:string ='';
username: string='';
name:string='';
password:string='';
email:string=''; }

header.ts

user= this.authservice.useraccountValue;
 constructor(private authservice:AuthService) {
    //this.user
this.authservice.user.subscribe(x => this.user = x);
console.log(this.user);}

header.html

<ul class="info_ul">
    <li>{{user.username}}</li>
    <li><a (click)="logout($event)">logout</a></li>
</ul>