'header' is not defined react/jsx-no-undef code example

Example 1: 'Link' is not defined react/jsx-no-undef

import { Link } from 'react-router-dom';

Example 2: 'App' is not defined react/jsx-no-undef

// 'App' is not defined react/jsx-no-undef
import App from "./App"; //import into index.js file