index.js: update babel/register to resolve both js and ts files

Author: clairep94

index.js

@@ -1,11 +1,14 @@
 if (process.env.NODE_ENV === 'production') {
-  process.env.webpackAssets = JSON.stringify(require('./dist/static/manifest.json'));
+  process.env.webpackAssets = JSON.stringify(
+    require('./dist/static/manifest.json')
+  );
   require('./dist/server.bundle.js');
   require('./dist/previewServer.bundle.js');
 } else {
   let parsed = require('dotenv').config();
   require('@babel/register')({
-    presets: ["@babel/preset-env"]
+    extensions: ['.js', '.jsx', '.ts', '.tsx'],
+    presets: ['@babel/preset-env', '@babel/preset-typescript']
   });
   require('regenerator-runtime/runtime');
   //// in development, let .env values override those in the environment already (i.e. in docker-compose.yml)