fix: #112 - default NestedKey to never

[kelsny]

Fixes #112

Modified files:

• packages/use-intl/src/useTranslations.tsx

It's just my comment with the ideas applied:

And in the conditional, I just check if NestedKey is never: [NestedKey] extends [never] ? ... : .... It seems to work fine.

You can find the fix here

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Name	Status	Preview	Updated
next-intl	✅ Ready (Inspect)	Visit Preview	May 27, 2022 at 9:05PM (UTC)

[amannn]

Hey @kelsny, this is incredibly nice of you to directly submit a PR! Thank you so much for your help!

[amannn]

From your issue comment:

When using generics as types for optional parameters, and the parameter is not given, the generic is defaulted to its constraint.
So I solved this (in a terrible way I did not test) by testing if the constraint extends NestedKey . Obviously, now that I think about it, this will break for objects with only one top-level property...
I also just learnt this very recently, so now I can solve this problem. I've given NestedKey a default "value" (it's actually a type, of course, but at the type-level I refer to types as "values") of never.
And in the conditional, I just check if NestedKey is never: [NestedKey] extends [never] ? ... : .... It seems to work fine.

I think I understand. Ultimately we want to check if namespace was provided at the type-level and never would mean that it wasn't. Makes sense to me! It's still a bit strange to me though why have to wrap the types into arrays for comparing them with extends.

But it's really great to see that this works! 👏

[amannn]

I tested your fix in a larger codebase where I'm using next-intl and it seems to work flawlessly. Thank you very much for your help @kelsny!