fix: notFound() and redirect() should return never

The reason being is you can't actually give JSON to these types, and the page goes away when these happen, so it's logically the same as throwing

It also cleans up unions; before, an empty object type could show up in the props type, but `never` "dissolves" itself in unions

package.json

@@ -14,7 +14,8 @@
     "test:e2e": "cross-env type=e2e jest --runInBand ./pages",
     "version": "npm run build",
     "postversion": "cp -r docs README.md package.json lib",
-    "release": "np --contents=./lib --message='release: cut the `%s` release' --no-yarn --no-2fa"
+    "release": "np --contents=./lib --message='release: cut the `%s` release' --no-yarn --no-2fa",
+    "typecheck": "tsc --noEmit"
   },
   "main": "./index.js",
   "source": "./src/index.ts",

pages/pending-nav.tsx

@@ -14,7 +14,7 @@ export const getServerSideProps = handle({
     await setTimeout(1000);
     toggle = !toggle;
     console.log('POST', toggle);
-    return redirect<never>(context.req.url!, 303);
+    return redirect(context.req.url!, 303);
   },
 });
 

src/responses.ts

@@ -14,11 +14,15 @@ export type ResponseInit = Pick<
 >;
 export type ResponseType = 'not-found' | 'redirect' | 'json';
 
-function createResponse<T>(
-  body: { [key: string]: any },
-  init: ResponseInit,
-  type: ResponseType,
-): TypedResponse<T> {
+function createResponse<T>({
+  body = {} as T,
+  init,
+  type,
+}: {
+  body?: T;
+  init: ResponseInit;
+  type: ResponseType;
+}): TypedResponse<T> {
   const response = new Response(JSON.stringify(body), init) as TypedResponse<T>;
   response.headers.set('x-next-runtime-type', type);
   return response;
@@ -27,9 +31,9 @@ function createResponse<T>(
 /**
  * Send the user a 404
  */
-export function notFound<TProps>(
+export function notFound(
   init: number | ResponseInit = 404,
-): TypedResponse<TProps> {
+): TypedResponse<never> {
   let responseInit: ResponseInit;
 
   if (typeof init === 'number') {
@@ -38,16 +42,16 @@ export function notFound<TProps>(
     responseInit = { status: 404, ...init };
   }
 
-  return createResponse({}, responseInit, 'not-found');
+  return createResponse<never>({ init: responseInit, type: 'not-found' });
 }
 
 /**
  * Redirect the user to another page. Defaults to temporary redirect.
  */
-export function redirect<TProps>(
+export function redirect(
   destination: string,
   init: number | ResponseInit | { permanent: boolean } = 302,
-): RuntimeResponse<TProps> {
+): RuntimeResponse<never> {
   let responseInit: ResponseInit;
 
   if (typeof init === 'number') {
@@ -61,7 +65,10 @@ export function redirect<TProps>(
   const headers = new Headers(responseInit.headers);
   headers.set('Location', destination);
 
-  return createResponse({}, { ...responseInit, headers }, 'redirect');
+  return createResponse<never>({
+    init: { ...responseInit, headers },
+    type: 'redirect',
+  });
 }
 
 /**
@@ -84,5 +91,9 @@ export function json<TProps>(
     headers.set('Content-Type', 'application/json; charset=utf-8');
   }
 
-  return createResponse(props, { ...responseInit, headers }, 'json');
+  return createResponse({
+    body: props,
+    init: { ...responseInit, headers },
+    type: 'json',
+  });
 }