fix iterator types (#21)

* chore: update flake.lock

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/f4f322d1424aa547eba9cb092f905f5ceb9b639c' (2024-07-29)
  → 'github:NixOS/nixpkgs/3563397b2f10ffa1891e1a6ce99d13d960d73acd' (2024-07-30)

* fix: types

src/v1/create_search_iterator_fn.ts

@@ -1,6 +1,7 @@
 import type { PagedResponse } from './paged_response.ts'
 import type { PagedRequest } from './paged_request.ts'
 
+// TODO(@joscha): this is a mess, simplify types here whilst preserving the required paged request/response types
 export const createSearchIteratorFn = <
     FN extends (r: PAGED_REQUEST) => Promise<PAGED_RESPONSE>,
     PAGED_REQUEST extends PagedRequest,
@@ -12,20 +13,25 @@ export const createSearchIteratorFn = <
         & string,
     SINGLE_RESPONSE = object,
 >(searchFn: FN, key: PAYLOAD_KEY) => {
+    type Single = ReturnType<FN> extends Promise<infer T> ? T : never
+    type Unwrapped = Single extends { [key in PAYLOAD_KEY]: infer T } ? T
+        : never
     async function* searchIterator(
-        params: Omit<PAGED_REQUEST, 'page_token'>,
-    ): AsyncGenerator<PAGED_RESPONSE[]> {
+        params:
+            & Omit<Parameters<FN>[0], keyof PagedRequest>
+            & Omit<PAGED_REQUEST, 'page_token'>,
+    ): AsyncGenerator<Unwrapped> {
         let page_token: string | undefined = undefined
         while (true) {
             const response: PAGED_RESPONSE = await searchFn(
                 // TODO(@joscha): remove cast
-                (page_token
-                    ? { ...params, page_token }
-                    : params) as PAGED_REQUEST,
+                (page_token ? { ...params, page_token } : params) as Parameters<
+                    FN
+                >[0],
             )
 
             // TODO(@joscha): remove cast
-            yield response[key] as unknown as PAGED_RESPONSE[]
+            yield response[key] as Unwrapped
 
             if (response.next_page_token === null) {
                 // no more pages to fetch