Hi, I'm trying to use a context enricher

const referrerList = [
  'pay.skrill.com',
  'commerce.coinbase.com',
  'paymentpage.ecommpay.com',
];

function checkReferrer({ system, client }) {
  if (referrerList.some((referrer) => system.page.referrer.includes(referrer))) {
    system.page.referrer = '';
  }
    return { client, system };
}

export default {
  async fetch(request, env, ctx) {
    const { system, client } = await request.json();
    const newContext = checkReferrer({ system, client });
    return new Response(JSON.stringify(newContext));
  }
};