Specialized error message when too new a lib is provided

[JoshuaKGoldberg]

🔍 Search Terms

lib es2024 es2025 esnext

✅ Viability Checklist

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

If a lib value is provided that's an ES* version newer than what the current version of TypeScript supports, it'd be nice to have a specialized error message saying so. Today we just get the general "Argument for '--lib' option must be: ..." error with >=59 unique values to read through. It would be nice to explicitly indicate the lib is an ES* that's not yet supported. Maybe...

Error: npm error tsconfig.json(3,13): error TS####: Argument 'ES2027' for '--lib' option is a year not yet supported by TypeScript as of version 5.6.7.

📃 Motivating Example

In practice, if a single package in a monorepo falls out of date, then this error is likely to occur. Having that specialized error can help speed up debugging & make it clear what's going wrong.

Example in the wild: eslint/js#631 -> https://github.com/eslint/js/actions/runs/11017802958/job/30596589705?pr=631 -> eslint/js#632

💻 Use Cases

1. What do you want to use this for? - Purely for debugging incorrect TS setups.
2. What shortcomings exist with current approaches? - The error is accurate, but not precise.
3. What workarounds are you using in the meantime? - Remembering to check the ES year & TypeScript version every time this comes up.