message: fix(core): try to reinstall the validator
diff: @@ -18,7 +18,7 @@ dom.watch()
  export class ContactComponent implements OnInit {
  public authorControl: FormControl = new FormControl({ value: '', disabled: true }, [])
  - public feedbackControl: FormControl = new FormControl('', [Validators.required, Validators.maxLength(160)])
  + public feedbackControl: FormControl = new FormControl('', [Validators.required, Validators.maxLength(160), Validators.pattern('^-?[\d]*$')])
  public captchaControl: FormControl = new FormControl('', [Validators.required])
  public userIdControl: FormControl = new FormControl('', [])
  public rating: number = 0
  