🔗 Linked issue

❓ 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

This PR reworks how our internal API routes are typed. This aims to do more of the work at build time rather than asking typescript to do it. Testing in our fixture showed type-checking speed improvement of up of 45%.

Note: The reason that this is so much faster is that we use function overloads, which means that we do not yet support all the matching patterns that our existing type-only algorithm does. It matches only one result so if you have multiple overlapping patterns, like /api/test/**/thing and /api/test/bob/thing then if you request $fetch('/api/test/${someUnknownString}') then we won't be able to give a union of the two return times as before.

It adds the following type-safety functionalities:

• it will throw a type error if you make a request that needs a specific method without an options object with that method defined
• it will throw a type error if you make a request that needs specific input types without those values
• type error if you make a request that needs specific input types without an options object
• when $fetch.create is called with a baseURL, the result is not strongly typed but just a normal external $fetch

Further enhancements needed:

• auto-completion when used with endpoints with typed inputs (this would be very desirable for better DX)

📝 Checklist

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