Angular CLI - Typescript throws: Cannot read property 'length' of undefined

Question

I run in angular 4 project with ng serve and i get error

Cannot read property \'length\' of undefined

but I don\'t have any property length in

Answer 1

In my case I did the following and it solved the issue:

1. Create environments folder (if not exist) in src of the Project C:\Users\abcd\Desktop\MyApp\src

2. Put the two files environment.ts and environment.prod.ts in environments folder.