Support Fastify v5

Preliminary Checks

I have reviewed the documentation: https://clerk.com/docs
I have searched for existing issues: https://github.com/clerk/javascript/issues
I have not already reached out to Clerk support via email or Discord (if you have, no need to open an issue here)
This issue is not a question, general help request, or anything other than a bug report directly related to Clerk. Please ask questions in our Discord community: https://clerk.com/discord.

Reproduction

Publishable key

pk_test_Zml0dGluZy15YWstOTguY2xlcmsuYWNjb3VudHMuZGV2JA

Description

When installing fastify v5, the backend immediately crashes with the following error:

[08:51:11 UTC] ERROR: fastify-plugin: @clerk/fastify - expected '4.x' fastify version, '5.0.0' is installed
    err: {
      "type": "FastifyError",
      "message": "fastify-plugin: @clerk/fastify - expected '4.x' fastify version, '5.0.0' is installed",
      "stack":
          FastifyError: fastify-plugin: @clerk/fastify - expected '4.x' fastify version, '5.0.0' is installed
      "code": "FST_ERR_PLUGIN_VERSION_MISMATCH",
      "name": "FastifyError",
      "statusCode": 500
    }

Environment

Having the same issue

Hi, thanks for the issue. The error comes from

javascript/packages/fastify/src/clerkPlugin.ts

Lines 26 to 29 in c49eaa7

    
           export const clerkPlugin = fp(plugin, { 
        
             name: '@clerk/fastify', 
        
             fastify: '4.x', 
        
           });

so it's expected to happen. Currently the plugin is only compatible with Fastify v4.

The migration guide is here for reference: https://fastify.dev/docs/latest/Guides/Migration-Guide-V5/

For example, they now require Node.js 20 whereas the Clerk package allows 18.17.0 or later. So we'll need to cut a new major version in doing this upgrade. We'll work on it 👍

Support for Fastify v5 has been added in @clerk/fastify@2.0.0. Please note that it's not backwards-compatible with Fastify v4, you will have to use Fastify v5.

	export const clerkPlugin = fp(plugin, {
	name: '@clerk/fastify',
	fastify: '4.x',
	});