Angular5 form form validation

ngOnInit () {

this.form = new FormGroup({
  email: new FormControl("email@163.com", [Validators.required]),
  password: new FormControl()
});

expected effect
clipboard.png

didn"t show up.
also reports an error

         <mat-form-field class="full-width" >
          <input matInput type="text"  placeholder="Email" formControlName="email" value="">
        </mat-form-field>
Mar.03,2021
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