Change logic around NON_STANDARD_NODE_ENV

[erulabs]

Currently, the NON_STANDARD_NODE_ENV warning is printed on every "next build" or "next start" when NODE_ENV is set to anything, even a valid string like "development" or "production". It is not printed when NODE_ENV is falsey, which I believe is why this issue is not more widely reported.

Changing || to && here I believe corrects the intention - warn the user when an invalid NODE_ENV is set during start or build.

Bug

• [ ] Related issues linked using fixes #number
• [ ] Integration tests added
• [ ] Errors have a helpful link attached, see contributing.md

Feature

• [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• [ ] Related issues linked using fixes #number
• [ ] Integration tests added
• [ ] Documentation added
• [ ] Telemetry added. In case of a feature if it's used or not.
• [ ] Errors have a helpful link attached, see contributing.md

Documentation / Examples

• [ ] Make sure the linting passes by running pnpm build && pnpm lint
• [ ] The "examples guidelines" are followed from our contributing doc

[erulabs]

Hey @ijjk, thank you! Since the output is a stdout warning that I'm now silencing in the case of a valid NODE_ENV, I'm not sure how to add a test-case. Do we have some sort of stdout capture? Seems like it would be a flaky test. This is cosmetic, so let me know how a test would work!