optimistic-dialog.ts

@Component({
  templateUrl: './add_comment_dialog.ng.html',
  changeDetection: ChangeDetectionStrategy.OnPush,
})
export class AddCommentDialog {
  comment: FormControl;

  constructor(
      readonly dialogRef: MatDialogRef<AddCommentDialog>,
      @Optional() @Inject(MAT_DIALOG_DATA) readonly errorPayload?:
          AddCommentErrorPayload,
  ) {
    this.comment = new FormControl('', [Validators.required]);
    if (this.errorPayload) {
      this.comment.setValue(this.errorPayload.errorComment);
    }
  }
}