Validate language code in translated content links

[nschonni]

Summary

Yari does a good job today of flagging when an internal link uses a language code link that doesn't exist (yet) and will fall back to the en-US version. Where it could be enhanced is to flag when an invalid language code is used in an internal link.

URL

https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleTimeString

Reproduction steps

1. Macro is using {{page('zh-US/docs/JavaScript/Reference/Global_Objects/DateTimeFormat','Parameters')}} with an invalid language code
2. Other ones i've come across:
   • /en/ & /zh/ under specified language code
   • /ja-US/

Expected behavior

If the link or macro path isn't in an allow list of supported languages, Yari should raise a warning. External links like MSDN that use language codes would be ignored.

Actual behavior

Warnings are raised that it will fall back to /en-US/ version, even if there is a correct localized document.

Device

Desktop

Browser

Firefox

Browser version

Stable

Operating system

Windows

Screenshot

No response

Anything else?

No response

Validations

• [X] I have read the Community Participation Guidelines.
• [X] I have verified that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• [X] I have checked that this is a concrete bug. For Q&A open a GitHub Discussion.

[caugner]

We would accept a community PR that extends build/flaws/broken-links.js to emit a flaw for /{locale}/docs links where {locale} is not a supported locale. 👍