fix: handle scenario of no process.env value for New Relic plugins

* Require env.config object after copying it into MFE

config/webpack.prod.config.js

@@ -24,22 +24,24 @@ const HtmlWebpackNewRelicPlugin = require('../lib/plugins/html-webpack-new-relic
 const commonConfig = require('./webpack.common.config');
 const presets = require('../lib/presets');
 
-/** This condition confirms whether the MFE has a JS-based configuration file and creates a copy of the file based
- * on the filepath given. If the environment variable exists, then an env.config.js(x) file will be created at the root
- * directory and its env variables can be accessed with getConfig().
+/** This condition confirms whether the configuration for the MFE has switched to a JS-based configuration
+ * as previously implemented in frontend-build and frontend-platform. If the environment variable exists, then
+ * an env.config.js file will be created at the root directory and its env variables can be accessed with getConfig().
  *
  * https://github.com/openedx/frontend-build/blob/master/docs/0002-js-environment-config.md
  * https://github.com/openedx/frontend-platform/blob/master/docs/decisions/0007-javascript-file-configuration.rst
  */
+
 const envConfigPath = process.env.JS_CONFIG_FILEPATH;
+let envConfig = {};
+
 if (envConfigPath) {
-  // This handles the possibility that env.config will have either a JS or JSX extension
   const envConfigFilename = envConfigPath.slice(envConfigPath.indexOf('env.config'));
+  fs.copyFileSync(envConfigPath, envConfigFilename);
 
-  fs.copyFile(envConfigPath, envConfigFilename, (err) => {
-    if (err) { throw err; }
-  });
-}
+  let newConfigFilepath = path.resolve(process.cwd(), envConfigFilename);
+  envConfig = require(newConfigFilepath);
+};
 
 // Add process env vars. Currently used only for setting the PUBLIC_PATH.
 dotenv.config({
@@ -63,12 +65,12 @@ if (process.env.ENABLE_NEW_RELIC !== 'false') {
     agentID: process.env.NEW_RELIC_AGENT_ID || 'undefined_agent_id',
     trustKey: process.env.NEW_RELIC_TRUST_KEY || 'undefined_trust_key',
     licenseKey: process.env.NEW_RELIC_LICENSE_KEY || 'undefined_license_key',
-    applicationID: process.env.NEW_RELIC_APP_ID || 'undefined_application_id',
+    applicationID: envConfig.NEW_RELIC_APP_ID || process.env.NEW_RELIC_APP_ID || 'undefined_application_id',
   }));
   extraPlugins.push(new NewRelicSourceMapPlugin({
-    applicationId: process.env.NEW_RELIC_APP_ID,
+    applicationId: envConfig.NEW_RELIC_APP_ID || process.env.NEW_RELIC_APP_ID,
     apiKey: process.env.NEW_RELIC_ADMIN_KEY,
-    staticAssetUrl: process.env.BASE_URL,
+    staticAssetUrl: envConfig.BASE_URL || process.env.BASE_URL,
     // upload source maps in prod builds only
     noop: typeof process.env.NEW_RELIC_ADMIN_KEY === 'undefined',
   }));