warning.js:34 warning: react-modal: app element is not defined.

warning.js:34 warning: react-modal: app element is not defined. please use modal.setappelement(el) or set appelement={el}. this is needed so screen readers don't see main content when modal is opened. it is not recommended, but you can opt-out by setting ariahideapp={false}

---> 위와 같은 에러 발생시

// index.js
const rootElement = document.getElementById("root");
ReactDOM.render(
  <StrictMode>
    <App />
  </StrictMode>,
  rootElement
);

// App.js
Modal.setAppElement('#root') //App.js

---> 이렇게 적어주면 된다고 한다.

출처
Modal.setAppElement(element)