错误: formGroup需要一个FormGroup实例。请传入一个；TypeError:无法读取未定义的属性“controls”

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup } from '@angular/forms';

@Component({
  selector: 'app-my-form',
  templateUrl: './my-form.component.html',
  styleUrls: ['./my-form.component.css']
})
export class MyFormComponent implements OnInit {
  myForm: FormGroup;

  constructor(private fb: FormBuilder) {}

  ngOnInit() {
    this.myForm = this.fb.group({
      name: [''],
      email: ['']
    });
  }
}

ngOnInit() {
  this.service.getData().subscribe(data => {
    this.myForm = this.fb.group({
      name: [data.name],
      email: [data.email]
    });
  });
}

<form [formGroup]="myForm">
  <input formControlName="name" placeholder="Name">
  <input formControlName="email" placeholder="Email">
</form>