无法读取未定义的属性'push‘- React错误

import React, { Component } from 'react';

class MyComponent extends Component {
  constructor(props) {
    super(props);
    this.state = {
      myArray: [] // 初始化一个空数组
    };
  }

  handleClick = () => {
    if (this.state.myArray) {
      this.state.myArray.push('new item'); // 使用push方法之前检查数组是否已定义
      this.setState({ myArray: this.state.myArray });
    }
  }

  render() {
    return (
      <div>
        <button onClick={this.handleClick}>Add Item</button>
      </div>
    );
  }
}

export default MyComponent;