refactor: replace var with const + add line break

Author: diogo405

index.js

@@ -26,7 +26,7 @@ app.use((err, req, res, next) => {
     });
 });
 
-var port = process.env.PORT || 3000;
+const port = process.env.PORT || 3000;
 app.listen(port, function() {
     console.log('listening on port ' + port);
-});
+});