无法在React Native "null is not an object“中调用另一个组件中的方法

import React, { forwardRef, useImperativeHandle } from 'react';
import { View, Text } from 'react-native';

const ChildComponent = forwardRef((props, ref) => {
  useImperativeHandle(ref, () => ({
    sayHello: () => {
      console.log('Hello from ChildComponent!');
    }
  }));

  return (
    <View>
      <Text>Child Component</Text>
    </View>
  );
});

export default ChildComponent;

import React, { useRef } from 'react';
import { Button, View } from 'react-native';
import ChildComponent from './ChildComponent';

const ParentComponent = () => {
  const childRef = useRef(null);

  const handlePress = () => {
    if (childRef.current) {
      childRef.current.sayHello();
    } else {
      console.log('ChildComponent is not ready yet.');
    }
  };

  return (
    <View>
      <ChildComponent ref={childRef} />
      <Button title="Call Child Method" onPress={handlePress} />
    </View>
  );
};

export default ParentComponent;