Integracion de Mercadopago CheckoutPro en ReactJS [Sin usar FunctionComponents o ClassComponents]

MercadoPagoCheckoutPro-ReactJS.ts

export const redirectToMercadoPago = (transactionId: string) => {
  const loadScript = (url: string, callback: () => void) => {
    let script = document.createElement('script');
    script.type = 'text/javascript';

    if (script.readyState) {
      script.onreadystatechange = () => {
        if (
          script.readyState === 'loaded' ||
          script.readyState === 'complete'
        ) {
          script.onreadystatechange = null;
          callback();
        }
      };
    } else {
      script.onload = () => callback();
    }
    script.src = url;
    document.getElementsByTagName('head')[0].appendChild(script);
  };

  const handleScriptLoad = () => {
    const mp = new window.MercadoPago(process.env.REACT_APP_MERCADOPAGO_KEY, {
      locale: 'es-AR'
    });
    mp.checkout({
      preference: {
        id: transactionId
      },
      autoOpen: true
    });
  };

  loadScript('https://sdk.mercadopago.com/js/v2', handleScriptLoad);
};

Hola!
El typescript me da problema sale "property readyState does not exist on type 'HTMLScriptElement'", expandiste el HtmlElement de alguna manera? gracias.