如何在angular 6表单控件验证器中一次只显示一个验证

import { AbstractControl, ValidatorFn } from '@angular/forms';

export function singleValidator(): ValidatorFn {
  return (control: AbstractControl): { [key: string]: any } | null => {
    // 在这里编写验证逻辑
    // 如果有错误，返回一个包含错误信息的对象
    // 如果没有错误，返回null
  };
}

import { Component } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { singleValidator } from './validators';

@Component({
  selector: 'app-my-component',
  template: `
    <form [formGroup]="myForm">
      <input type="text" formControlName="myControl">
      <div *ngIf="myForm.get('myControl').errors">
        <div *ngIf="myForm.get('myControl').hasError('error1')">Error 1</div>
        <div *ngIf="myForm.get('myControl').hasError('error2')">Error 2</div>
        <div *ngIf="myForm.get('myControl').hasError('error3')">Error 3</div>
      </div>
    </form>
  `,
})
export class MyComponent {
  myForm: FormGroup;

  constructor(private fb: FormBuilder) {
    this.myForm = this.fb.group({
      myControl: ['', [Validators.required, singleValidator()]],
    });
  }
}