singup.component.html

<div style="text-align:center">
    <h1>
      Signup
    </h1>
  </div>

  <input #username type='text' placeholder='username'>
  <input #email type='text' placeholder='email'>
  <input #password1 type='password' placeholder='password1'>
  <input #password2 type='password' placeholder='password2'>
  <button (click)="signup(username.value, email.value, password1.value, password2.value)">signup</button>
  <p>{{ error?.message }}</p>
  <p *ngIf="error">{{ error?.error | json }}</p>