Error: MapboxGL: Access token not found when initializing map in production

Goal: Ensure that a Mapbox GL JS map initializes successfully in a production build without depending on the automatic token injection provided by a local development server.

Constraints: The access token must be assigned to mapboxgl.accessToken before any map instance is created, yet some build tools may strip or replace process.env variables, leaving the token undefined in the final bundle. It is unclear whether the token should be baked into the bundle at build time, supplied via a runtime configuration endpoint, or handled through another secure mechanism, and how to confirm its presence without executing the map code.

• What is the recommended approach to inject the Mapbox access token into a production bundle while keeping it secure?
• Should the token be set via a build‑time environment variable that is replaced at compile time, fetched at runtime from a protected endpoint, or managed through another method?
• How can developers verify that the token is present in the final bundle without triggering map initialization?