empty ee folder causes `Can't resolve ee_else_ce` error

Running CE, create empty ee/ folder. I sometimes have leftover ee/spec folders if running tests when changing branches from EE to CE

Webpack build fails and prints errors

e.g.

11:42:16 webpack.1               | ERROR in ./main.js
11:42:16 webpack.1               | Module not found: Error: Can't resolve 'ee_else_ce/main_ee' i

Possible solutions

a) add a more thorough check to is_ee_env
b) print a warning
c) rm ee/