React/Ionic routing:无法读取未定义的属性“”startsWith“”

const result = someVariable?.startsWith('someString');

if (someVariable) {
  const result = someVariable.startsWith('someString');
}

const result = (someVariable || '').startsWith('someString');

import React, { useEffect, useState } from 'react';

const MyComponent = () => {
  const [data, setData] = useState(null);

  useEffect(() => {
    // 模拟数据加载
    setTimeout(() => {
      setData('someString');
    }, 1000);
  }, []);

  if (!data) {
    return <div>Loading...</div>;
  }

  const result = data.startsWith('someString');

  return (
    <div>
      {result ? 'Starts with someString' : 'Does not start with someString'}
    </div>
  );
};

export default MyComponent;