False negative type error for async middleware

[markedwards]

There seems to be a subtle problem with the typing of RouteMiddleware if the function is async, and it can return both a NextResponse and some custom options.

Example:

import { TypedNextResponse, route, routeOperation } from "next-rest-framework";

async function sleep() {
  await new Promise(() => setTimeout(() => {}, 1000));
}

export const { GET } = route({
  hello: routeOperation({
    method: "GET",
  })
    .middleware(async () => {
      await sleep();
      if (Math.random() > 0.5) {
        return {
          foo: "bar",
        };
      }
      return TypedNextResponse.json(
        {
          message: "",
        },
        {
          status: 400,
        },
      );
    })
    .handler((_req, _ctx, { foo }) => {
      console.log(foo);
    }),
});

This raises Type '{ foo: string; }' is not assignable to type 'void | NextResponse<unknown> | TypedNextResponseType<unknown, number, AnyContentTypeWithAutocompleteForMostCommonOnes>'. ts(2345). Also, the foo argument in the handler is unknown.

If the function is made sync (and the await sleep() line is removed, there's no type error. So it seems to be some unimplemented type condition in the async case.

[blomqma]

Thanks, this should be fixed in v6.0.0.

[markedwards]

Confirmed this is fixed. One slightly odd thing is I have to wrap my object like so:

      return {
        ...obj,
      };

Otherwise I get Type 'Foo' is not assignable to type 'BaseOptions'. Index signature for type 'string' is missing in type 'Foo'. Presumably because the object is just described by an interface and does not inherit from Record<string, unknown>?

Otherwise it works great though. Thanks!