fix(types): make $Fetch types less complex (#1059)

src/build.ts

@@ -92,7 +92,7 @@ export async function writeTypes(nitro: Nitro) {
       routeTypes[mw.route][method] = [];
     }
     routeTypes[mw.route][method].push(
-      `Awaited<ReturnType<typeof import('${relativePath}').default>>`
+      `Simplify<Serialize<Awaited<ReturnType<typeof import('${relativePath}').default>>>>`
     );
   }
 
@@ -117,6 +117,7 @@ export async function writeTypes(nitro: Nitro) {
 
   const routes = [
     "// Generated by nitro",
+    "import type { Serialize, Simplify } from 'nitropack'",
     "declare module 'nitropack' {",
     "  type Awaited<T> = T extends PromiseLike<infer U> ? Awaited<U> : T",
     "  interface InternalApi {",

src/types/fetch.ts

@@ -1,6 +1,5 @@
 import type { RouterMethod } from "h3";
 import type { FetchRequest, FetchOptions, FetchResponse } from "ofetch";
-import type { Serialize } from "./serialize";
 import type { MatchedRoutes } from "./utils";
 
 // An interface to extend in a local project
@@ -13,12 +12,11 @@ export type NitroFetchRequest =
   // eslint-disable-next-line @typescript-eslint/ban-types
   | (string & {});
 
-// TODO: re-enable Simplify
 export type MiddlewareOf<
   Route extends string,
   Method extends RouterMethod | "default"
 > = Method extends keyof InternalApi[MatchedRoutes<Route>]
-  ? Exclude<Serialize<InternalApi[MatchedRoutes<Route>][Method]>, Error | void>
+  ? Exclude<InternalApi[MatchedRoutes<Route>][Method], Error | void>
   : never;
 
 export type TypedInternalResponse<

src/types/index.ts

@@ -1,4 +1,5 @@
 export * from "./fetch";
+export * from "./serialize";
 export * from "./nitro";
 export * from "./handler";
 export * from "./utils";