Fixes lint errors.

pages/_app.tsx

@@ -1,5 +1,7 @@
 import createCache from '@emotion/cache';
 import { CacheProvider } from '@emotion/react';
+import React from 'react';
+import PropTypes from 'prop-types';
 
 const cache = createCache({ key: 'next' });
 
@@ -9,4 +11,13 @@ const App = ({ Component, pageProps }) => (
   </CacheProvider>
 );
 
+App.propTypes = {
+  Component: PropTypes.element.isRequired,
+  pageProps: PropTypes.oneOfType([PropTypes.object]),
+};
+
+App.defaultProps = {
+  pageProps: {},
+};
+
 export default App;

pages/news.jsx

@@ -1,4 +1,5 @@
 import styled from '@emotion/styled';
+import React from 'react';
 
 const P = styled.p`
   color: black;
@@ -9,6 +10,6 @@ const P = styled.p`
   }
 `;
 
-const News = () => <P>{'News'}</P>;
+const News = () => <P>News</P>;
 
 export default News;