UnhandledPromiseRejectionWarning: TypeError: невозможно использовать оператор in

Question

У меня есть json, который выглядит так:

 {"accept":"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8","accept-language":"en-US","referer":"https://www.sahibinden.com/en/cars?sorting=date_desc","user-agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.2 Safari/605.1.15","x-origin-dc":"gytp","x-forwarded-proto":"https","x-forwarded-for":"39.41.162.210","x-tls-version":"771","x-client-srcport":"52468","istl-infinite-loop":"1","x-j3popqvx-f":"A1wraNpyAQAAV49ZLH5TS8mT9x5JDpH7WJPlwQNv4h7U5JxYfxEOUa_Z7o5pAScpotL6K1FB4hcAAOfvAAAAAA==","x-j3popqvx-b":"v2j9i8","x-j3popqvx-c":"AIC8ZdpyAQAAovzca2FjGMY3Jtuxj0kootlxgwYXmgR4ysP_sW3w2brE25d3","x-j3popqvx-d":"AAaCxAiBBKCMgcGASZAQgICAACJt8Nm6xNuXd6oclOq4s6T2AswaceOl4XDPiTRAQwvQBLY","x-j3popqvx-z":"q","x-j3popqvx-a":"H0n5x-7ClCL8mvgjZGwp=LFdx5qCaBrVfu_25mQ4xoKcswK-DbK1HOW0SOr-=E0sYFM0NGXM9hrrlbk_7G=0LLC8gtaz6cpfbhcWDiS97Xfhsk6=u9Fn1ji8lEH=nSXTjVmIn6fGygd9rFFKTp3BuPbPf8sxfSgphtwEvssfLyS=8WYWwS3z-zx7hwsSlfsLkMacgb5vH=tJIypfYWPJnT9oCTX=OpxALO6tHqXnwG2qDcDb05Be_JOzN6ZWfuZSJuH6KooV-YQ_ZCg7FJFdzQbkm_66ZWEXWcL=pJ9PWlZeQI6lJHI1py4Dj-r8uKoWczWXeqmGLVnD1cN-3PRohoiCcmn9i1LyEJT5ln41uBeNPYg6_VfJV6BWeTH1PejG3unc1TZbPVfJPqIrrMw0m_JcC5WApCsTz4LpVmPos_1zJiW8TftQDQxEkSwy_PZjB8n_VFOyO5f_wyTuhoI8CtnX=evhszdzNXb4hbClv-x=YmySDsWQuB-1LM1rFKTP9qJ55iCV0N3ATK3bFoetDNpSTDbsenKmdOdXl6u38ZnA1uOhNClQlwdLdWIeSw9rmjFZxscqLtXVsaK35MRY3bM4ck7SAfh2umIPaYSuv9GiNzGQI--ERF22THKDYgENZH4CNXzwseYT1cc4xeuI1SMEcfGt=Xpx=ycOooSjmGS5Jr0NWjBkAmpjeZEY047vJDxf6O4QeJXs90ZJwC0laouDhvd1Id_byuF6MwPNF-IrWWKVSPBZO6I3OBe3C5K-82dLqkkXQBsj9i8B7zMLOItJttZZJVHPajftduxf76D1tPJItczLhLcalt3WfJ3g=LKJHAQS=ssLX-n_dBkjlqHk=bT-xAz0jqFwdrNhRgac_HA87qct5Xq7BwIy-sc9bhHulyjdTX1IP0cLHx1pHsA0ClwN9TR-dsoifsFKiOj4EtFkvD7dJTeR1ZQTu7=BXxC0SrbCPyYnHimtnurNdI28RW3lPZXeQ6dlFrCtwa54OKntVhuBWMHVJMs1cw0ZzILhMayHKewZ363SFzzxsbCfRkm3-69h2_cuq0Vw98jg391MrhhklpnQOdeIDZY-f2VC58OAE2OYy3gQ2epPWD_NQ2lROWencbeNrCD1exkRe2KrV5AoRcAxN=nk37YvYOw9LvCVJDdY5pivM5rgYCqJc2b1_joYckDsi6e4_YxQw2i9I7j3msudTZOnai=jchvPZjokiRCpfncRxO7Z_alOuBA9M8ef8fM0WNpuX4xoLQlEyL26urjKIEJ1eqp7hA7syVWT7_VTpyJ94tG_te9yvDWp2g978rvWpArklcYmrAXbqsYILbquwa751KBfCEcpjNQG9YCZDjbA5B5jXaI-odDyg4JEF3e5YaE_MiOAA1i8Mt209roSZ5hrfQnibrwjO53NdOiYO9v=PVDlmKjpQZZjHZpZwLzqoD83LJ8VJDlMvw9980KXHjuVuAOameb0EEDOaxO0HHT76qzq2RKJgnosTbP=udGYsC5RvJoVAtHMX0eh-T8ZS5NAzsjR=bWEl=4sAWQw27Bl86vaRVe26HkBqDVdWV8LeqljHprvER_DalV5yhgjN1Rq0X=tTYo8QZ00TKdo_V5xLh3woReRfNueZgyDAMfJ40PqA=i9FjtsEGrxjFjCDREJiNce=bG-hFKE7VBc0JYpaJB55k2EjklgdOoKgybqs3X0kLvCqVjVCNlh0dY1evI7xwHdmTqCBB1L5h52g5haRNBfFi=qAQWnbkyyqaywtSSoBuc3fnSViCj_pQuT8fIX70Fow0wV=yew3CX9yCc_NieEtNKskmlqL5YbWaFfvZOxCdnm91mnzehsliKIhv-jScAWR3AKYi1MiQEfl6LsBCld=28KOFB6HDJ=SB91OM1I2z=IHYcGhXwqqB6wMLDkzITJ3hgQFZQmfCrRHPPNtcD=x0uJ6iRRsze9ip9MdXIWovr8b2y7qxn7kbTiMsM-4mW1hSA3VLWX5CiyI2szMLCxTfJMcnqwbFqvawSEvzcu3w72FGWrcSSY0kkgbibkRyDcQYBM_rEjLPs9sYINY1sMEftTSza=mGGxISzB0tcZsveP_bm_RHwPFVZHhrBubAc=AbXJ2u3TiZ64JIm6=fKt3oggI2HJpp3Lkb7f_WXE0R2lXRkW4a44OJ_57V6t6C_7wC_nlPGWpc0GRiS9TulF8TBEkJIMr1_t2Q2FJbP9iiy7IK=VH2e_LlM5jPegm4mY-N9b7k74SWVtfxTgmf1K0vJvIse3bcuzXRJLXVoENlGGDZ4QqQkmd6dEH8z=rCc-o4Ocsw4LkYCKZz4EeYfP"}

Я хочу иметь возможность искать, существует ли ключ в этом json или нет. Я пробую это делать

    headers = {}
 

    page.route('**/*', route => {
    const request = route.request()
    //console.log(request.url(), JSON.stringify(request.headers()));
    headers = JSON.stringify(request.headers());
    if("x-j3popqvx-a" in headers){

      console.log(headers);
    }
    return route.continue();
  });
  let pageRes = await page.goto(url);
  await page.waitForTimeout(3 * 1000)
  await page.unroute("**/*");

Но это дает мне исключение

UnhandledPromiseRejectionWarning: TypeError: Cannot use 'in' operator to search for 'x-j3popqvx-a' in ....

Вот воспроизводимый код;

const { webkit } = require('playwright');

(async () => {
  const browser = await webkit.launch();
  const context = await browser.newContext();
  const page = await context.newPage();

  // Log and continue all network requests
  headers_u = {}
  page.route('**/*', route => {
    const request = route.request()
    //console.log(request.url(), JSON.stringify(request.headers()));
    headers = JSON.stringify(request.headers());
    if("x-j3popqvx-a" in headers){

      console.log(headers);
    }
    
    return route.continue();
  });

  let url = await page.goto('https://www.sahibinden.com/en/cars?sorting=date_desc');
  //console.log("headerw");
  //console.log(headers)
  await page.waitForTimeout(3 * 1000)
  
  await browser.close();
})();

Это воспроизводимый код, который можно использовать для тестирования.