My Next Js app isn't building and returing a type error, how do I fix?

If you're encountering a type error while attempting to build your Next.js app due to improper handling of the authOptions export, here are a few solutions:

1. Move authOptions to a Separate File:

Separate authOptions into a different file, for instance, authOptions.js, and import it into your [...nextauth]/route.js file:

// authOptions.js
import { AuthOptions } from "next-auth";
import GoogleProvider from 'next-auth/providers/google';

export const authOptions: AuthOptions = {
    providers: [
        GoogleProvider({
            clientId: process.env.GOOGLE_ID,
            clientSecret: process.env.GOOGLE_SECRET,
        }),
    ],
};

// [...nextauth]/route.js
import { authOptions } from "./authOptions";

const handler = NextAuth(authOptions);

export { handler as GET, handler as POST};

2. Configure Next.js to Ignore TypeScript Errors:

Alternatively, you can disable TypeScript error checking during the build process by adding the following configuration to your next.config.js file:

module.exports = {
  typescript: {
    // !! WARN !!
    // Dangerously allow production builds to successfully complete even if
    // your project has type errors.
    // !! WARN !!
    ignoreBuildErrors: true,
  },
};

3. Ensure Proper File Structure:

Ensure that your NextAuth-related files are organized as follows:

• pages/api/auth/[...nextauth].ts: This file handles authentication.
• lib/authOptions.ts: This file contains the authOptions configuration.

4. Export Only Supported Methods:

In your [...nextauth]/route.js file, ensure that you only export supported HTTP methods, such as GET, POST, and others.

5. Check for Import Errors:

Verify that your imports are correct. Ensure that you're importing NextAuthOptions and NextAuth from next-auth/next.

6. Avoid Exporting Arbitrary Objects:

Avoid exporting arbitrary objects from API routes. You can only export HTTP methods or other supported objects.

By implementing these solutions, you should be able to resolve the type error and successfully build your Next.js application.