fix(nuxt): infer useFetch method when generic is passed

[Gypsophyllite]

🔗 Linked issue

resolves #19077

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

I provided a workaround before, but this issue doesn't get solved.

I find that just change the method type 'get' extends AvailableRouterMethod<ReqT> ? 'get' : AvailableRouterMethod<ReqT> into AvailableRouterMethod<ReqT>, and all works fine as I see

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[danielroe]

Would you be able to add a test case in test/fixtures/basic/types.ts that was failing before this PR?

[Gypsophyllite]

@danielroe I added one, btw, setting the return type and request method explicitly will easily reproduce.

[danielroe]

Thanks! I've gone ahead and pushed a failing test to show why the type is written as is.

[danielroe]

What about this instead?

Suggested change

	Method extends AvailableRouterMethod<ReqT> = AvailableRouterMethod<ReqT>,
	Method extends AvailableRouterMethod<ReqT> = ResT extends void ? 'get' extends AvailableRouterMethod<ReqT> ? 'get' : AvailableRouterMethod<ReqT> : AvailableRouterMethod<ReqT>,

[Gypsophyllite]

Thanks! You are right. I have updated it.

[Gypsophyllite]

I also find the reason of broken type when passing uppercase method, maybe its a nitro type error in fetch.ts.
Another PR in nitro

[danielroe]

Nice work - thanks! I think we can go ahead and merge this PR (as it fixes one issue without introducing any regressions) and then update test once nitro PR is merged..