fix(ts): wrap adapter option in ReturnType (#1887)

* fix(ts): wrap adapter option in ReturnType

* test(ts): fix adapter tests

types/adapters.d.ts

@@ -124,7 +124,7 @@ export type Adapter<
   P = Profile,
   S = Session
 > = (
-  config: C,
+  config?: C,
   options?: O
 ) => {
   getAdapter(appOptions: AppOptions): Promise<AdapterInstance<U, P, S>>

types/index.d.ts

@@ -127,7 +127,7 @@ export interface NextAuthOptions {
    * [Default adapter](https://next-auth.js.org/schemas/adapters#typeorm-adapter) |
    * [Community adapters](https://github.com/nextauthjs/adapters)
    */
-  adapter?: Adapter
+  adapter?: ReturnType<Adapter>
   /**
    * Set debug to true to enable debug messages for authentication and database operations.
    * * **Default value**: `false`

types/tests/server.test.ts

@@ -65,7 +65,7 @@ const exampleVerificationRequest = {
   expires: new Date(),
 }
 
-const adapter: Adapter = () => {
+const MyAdapter: Adapter = () => {
   return {
     async getAdapter(appOptions: AppOptions) {
       return {
@@ -190,7 +190,7 @@ const allConfig: NextAuthTypes.NextAuthOptions = {
       return undefined
     },
   },
-  adapter,
+  adapter: MyAdapter(),
   useSecureCookies: true,
   cookies: {
     sessionToken: {