NextJs build step

[dsteinbach-ep]

Since the idea of react-env is to "build once, run anywhere" how do I handle building a NextJs app upfront before knowing which environment the built app will run in? It cannot safely rely on defaults in .env file if for example I need to fetch environment-specific CMS content upfront. Am I misunderstanding the use case of react-env? Thanks and sorry this is not really an issue - I am just confused.