What version of starlight are you using?

0.38.3

What version of astro are you using?

6.1.6

What package manager are you using?

pnpm

What operating system are you using?

mac

What browser are you using?

N/A

Describe the Bug

After updating TypeScript to v6, I got the following error when running tsc --noEmit:

> tsc --noEmit

node_modules/.pnpm/@[email protected][email protected]_@[email protected][email protected][email protected]_/node_modules/@astrojs/starlight/utils/i18n.ts:196:38 - error TS2339: Property 'language' does not exist on type 'never'.

196  return wellKnownRTL.includes(locale.language) ? 'rtl' : 'ltr';
                                         ~~~~~~~~


Found 1 error in node_modules/.pnpm/@[email protected][email protected]_@[email protected][email protected][email protected]_/node_modules/@astrojs/starlight/utils/i18n.ts:196

It seems that this is caused by the fact that TypeScript v6 has a newer DOM library; thus, locale becomes never in this line after the two if statements above.

For a short-term workaround, we can just add a @ts-ignore comment for this line; In the long term, #3572 should be the correct path to avoid such issues.

Link to Minimal Reproducible Example

https://github.com/issueset/starlight-ts-6-issue.git

Participation

• I am willing to submit a pull request for this issue.