feat: export middleware function types

There are now types exported that you can use to type middleware
functions that are defined apart from their use. Example:

```ts
const requestMiddleware: RequestMiddleware = async (request) => {
  return {
    ...request,
    headers: {
      ...request.headers,
      'x-auth-token': await getAccessToken(),
    },
  }
}

const _client = new GraphQLClient(endpoint, { requestMiddleware })
```

examples/other-middleware.ts

@@ -1,11 +1,9 @@
-/* eslint-disable */
-
 /**
  * It's possible to use a middleware to pre-process any request or handle raw response.
  */
 
 import { GraphQLClient } from '../src/index.js'
-import type { RequestMiddleware } from '../src/types.js'
+import type { RequestMiddleware, ResponseMiddleware } from '../src/types.js'
 
 const endpoint = `https://api.spacex.land/graphql/`
 
@@ -17,10 +15,12 @@ const getAccessToken = () => Promise.resolve(`some special token here`)
    */
 
   const requestMiddleware: RequestMiddleware = async (request) => {
-    const token = await getAccessToken()
     return {
       ...request,
-      headers: { ...request.headers, 'x-auth-token': token },
+      headers: {
+        ...request.headers,
+        'x-auth-token': await getAccessToken(),
+      },
     }
   }
 
@@ -46,14 +46,13 @@ const getAccessToken = () => Promise.resolve(`some special token here`)
    * Response middleware example (log request trace id if error caused):
    */
 
-  // @ts-expect-error TODO export a response middleware type
-  const responseMiddleware = (response: Response<unknown>) => {
-    if (response.errors) {
+  const responseMiddleware: ResponseMiddleware = (response) => {
+    if (!(response instanceof Error) && response.errors) {
       const traceId = response.headers.get(`x-b3-trace-id`) || `unknown`
       console.error(
         `[${traceId}] Request error:
         status ${response.status}
-        details: ${response.errors}`
+        details: ${response.errors.map((_) => _.message).join(`, `)}`
       )
     }
   }

src/index.ts

@@ -9,6 +9,7 @@ import {
 } from './parseArgs.js'
 import { resolveRequestDocument } from './resolveRequestDocument.js'
 import type {
+  BatchRequestDocument,
   FetchOptions,
   GraphQLClientRequestHeaders,
   GraphQLClientResponse,
@@ -17,10 +18,10 @@ import type {
   MaybeLazy,
   RequestConfig,
   RequestMiddleware,
+  ResponseMiddleware,
   VariablesAndRequestHeadersArgs,
 } from './types.js'
 import {
-  BatchRequestDocument,
   BatchRequestsExtendedOptions,
   BatchRequestsOptions,
   ClientError,
@@ -43,7 +44,9 @@ export {
   RawRequestOptions,
   RequestDocument,
   RequestExtendedOptions,
+  RequestMiddleware,
   RequestOptions,
+  ResponseMiddleware,
   Variables,
 }
 

src/types.ts

@@ -96,7 +96,7 @@ export interface RequestConfig extends Omit<RequestInit, 'headers' | 'method'>,
   method?: HTTPMethodInput
   headers?: MaybeLazy<GraphQLClientRequestHeaders>
   requestMiddleware?: RequestMiddleware
-  responseMiddleware?: (response: GraphQLClientResponse<unknown> | Error) => void
+  responseMiddleware?: ResponseMiddleware
   jsonSerializer?: JsonSerializer
 }
 
@@ -144,9 +144,10 @@ export interface BatchRequestsExtendedOptions<V extends Variables = Variables>
   url: string
 }
 
-export type RequestMiddleware<V extends Variables = Variables> = (
-  request: RequestExtendedInit<V>
-) => RequestExtendedInit | Promise<RequestExtendedInit>
+export type ResponseMiddleware = (response: GraphQLClientResponse<unknown> | Error) => void
+
+// prettier-ignore
+export type RequestMiddleware<V extends Variables = Variables> = (request: RequestExtendedInit<V>) => RequestExtendedInit | Promise<RequestExtendedInit>
 
 type RequestExtendedInit<V extends Variables = Variables> = RequestInit & {
   url: string

tests/exports.ts

@@ -0,0 +1,2 @@
+/* eslint-disable */
+import { RequestMiddleware, ResponseMiddleware } from '../src/index.js'