fix cjs files facebook/create-react-app#12700

config/webpack.config.js

@@ -438,7 +438,7 @@ module.exports = function (webpackEnv) {
             // Process any JS outside of the app with Babel.
             // Unlike the application JS, we only compile the standard ES features.
             {
-              test: /\.(js|mjs)$/,
+              test: /\.(js|mjs|cjs)$/,
               exclude: /@babel(?:\/|\\{1,2})runtime/,
               loader: require.resolve("babel-loader"),
               options: {