Always include either development or production in exportConditions

[benmccann]

• Rollup Plugin Name: @rollup/plugin-node-resolve
• Rollup Plugin Version: 15.3.0

Expected Behavior / Situation

It would be nice if exportConditions always included development or production

vite build will automatically set the production condition while vite dev will automatically set the development condition

References:
https://vite.dev/config/shared-options#resolve-conditions
https://vite.dev/guide/env-and-mode#node-env-and-modes

Libraries like Svelte rely on this for tree-shaking out parts of its bundle or returning different modules based on the value. This works automatically in Vite, but requires extra configuration in Rollup

Actual Behavior / Situation

exportConditions is empty by default

Modification Proposal

If the user has not provided either production or development then set production if NODE_ENV is undefined or production and development otherwise.