Hono treats empty object {} as type never for RPC

[meows]

What version of Hono are you using?

4.6.19

What runtime/platform is your app running on? (with version if possible)

Bun

What steps can reproduce the bug?

Create any route and simply return c.json({}). It will be inferred as type never.

const app = new Hono()
app.get("/", async (c) => c.json({}))

This behavior is specified in the source code:

{
  json(): F extends "text" 
    ? Promise<never> 
    : F extends "json" 
      ? Promise<BlankRecordToNever<T>> 
      : Promise<unknown>
}

This makes no sense as {} is valid JSON, and the response at the other end is in fact {} and not never.

What is the expected behavior?

This behavior is very surprising because this is valid JSON being mistyped. This behavior should at least be very clearly specified in the docs.

What do you see instead?

No response

Additional information

No response

[yusukebe]

HI @meows

This is a bug. #3868 can fix it. This is not a breaking change, but It may affect some users. So, it will be included in the next minor release instead of a patch release. Thank you!