CloudFlare worker to query permesso di soggiorno status

permesso.js

/**
 * Welcome to Cloudflare Workers! This is your first worker.
 *
 * - Run "npm run dev" in your terminal to start a development server
 * - Open a browser tab at http://localhost:8787/ to see your worker in action
 * - Run "npm run deploy" to publish your worker
 *
 * Learn more at https://developers.cloudflare.com/workers/
 */

async function get(pass) {
  const OPEN_TAG = "<![CDATA[";
  const CLOSE_TAG = "]]>";

  const url = `https://questure.poliziadistato.it/servizio/stranieri?lang=english&pratica=${pass}&invia=Submit&mime=4`;
  const response = await fetch(url);
  if (!response.ok) {
    throw new Error(`${response.status} ${response.statusText}`);
  }

  const text = await response.text();
  const start = text.indexOf(OPEN_TAG);
  const end = text.indexOf(CLOSE_TAG, start);

  if (start !== -1 && end !== -1)
    return text.substring(start + OPEN_TAG.length, end);

  throw new Error("Invalid response format");
}

export default {
  async fetch(request, env, ctx) {
    const url = new URL(request.url);

    if (url.pathname !== "/proxy")
      return new Response("Not Found", { status: 404 });

    const pass = url.searchParams.get("pass");
    if (!pass)
      return new Response("Password can not be empty", { status: 400 });

    try {
      const msg = await get(pass);
      return new Response(msg, {
        headers: { "Content-Type": "text/plain" },
      });
    } catch (error) {
      return new Response(`Error: ${error.message}`, { status: 500 });
    }
  },
};