add initial files

.erb/scripts/check-port-in-use.js

@@ -0,0 +1,16 @@
+import chalk from 'chalk';
+import detectPort from 'detect-port';
+
+const port = process.env.PORT || '4343';
+
+detectPort(port, (err, availablePort) => {
+  if (port !== String(availablePort)) {
+    throw new Error(
+      chalk.whiteBright.bgRed.bold(
+        `Port "${port}" on "localhost" is already in use. Please use another port. ex: PORT=4343 npm start`
+      )
+    );
+  } else {
+    process.exit(0);
+  }
+});