After Writing in the constructor parameter the router linkstop working

Question

follow is my code, if I emty the construction parameter thecode will work.but Likethis router linkwill not work.

import { Component, OnInit } from '@angular/core';
import { AuthService } from '../auth.service';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.scss']
})
export class LoginComponent implements OnInit {

  constructor(private afAuth : AuthService) { }

  ngOnInit(): void {
  }
  login(){
   
  }

}