[Bug?]: Env variable substitution syntax causes an Internal Error when used within injectEnvironmentFiles option

[SimpleCreations]

Self-service

• I'd be willing to implement a fix

Describe the bug

As per docs:

Environment variables can be accessed from setting definitions by using the ${NAME} syntax when defining the values. By default Yarn will require the variables to be present, but this can be turned off by using either ${NAME-fallback} (which will return fallback if NAME isn't set) or ${NAME:-fallback} (which will return fallback if NAME isn't set, or is an empty string).

This syntax works in many fields in .yarnrc.yml, but not in injectEnvironmentFiles, in which Yarn throws an exception:

Internal Error: Invalid configuration key "enableColors"
    at t.get (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:148:24085)
    at Gs (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:140:58823)
    at Object.pretty (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:140:64888)
    at Ut (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:140:59309)
    at t.useWithSource (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:148:22779)
    at t.find (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:148:17411)
    at async Rve (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:744:6254)
    at async HDt (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:744:7600)
    at async Lk (/Users/USER/.cache/node/corepack/v1/yarn/4.6.0/yarn.js:745:142)

To reproduce

1. Create a package.json file:

   {
     "name": "yarn-injectenvironmentfiles-bug-repro",
     "packageManager": "[email protected]",
     "private": true
   }

2. Create a .yarnrc.yml file:

   injectEnvironmentFiles:
     - ".env.${APPLICATION_ENV}"

3. Create an empty .env.production file
4. Run

   corepack enable
   export APPLICATION_ENV=production
   yarn

5. Observe an internal error thrown by Yarn

Expected behavior

No exception is thrown, yarn.lock is created, and future scripts are run with env variables defined in .env.production.

Actual behavior

An internal error is thrown.

Environment

System:
    OS: macOS 15.2
    CPU: (10) arm64 Apple M1 Pro
  Binaries:
    Node: 22.13.1 - /private/var/folders/48/krhvg1rs02x0vdk6fkj994440000gp/T/xfs-ed5488c4/node
    Yarn: 4.6.0 - /private/var/folders/48/krhvg1rs02x0vdk6fkj994440000gp/T/xfs-ed5488c4/yarn
    npm: 10.9.2 - /opt/homebrew/bin/npm

Additional context

No response