fastify-static | Plugin for serving static file | Internationalization library

i've been struggling a lot with fastify-passport library, mainly because it seems that nobody uses it and there aren't any good examples or issues related to it

anyhow, i have some routes defined like this:

Make files/images available to be access, when we navigate to

localhost:8000/properties/files/[image name]

localhost:8000/properties/files/1635843023660-profile.jpg

File Structure

I am working on an SSR server. I have a single catch-all dynamic route - loader for all GET requests, and I am using fastify-static to handle everything else.

I am having a simple Fastify server hosted with Heroku. But, it seems not working ! But, it seemed all right during the development! The error I get is: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 60 seconds of launch. Full error I am getting:

Here is the code I am using:
server.js:

I'm using fastify's fastify-static plugin, and need to transform files that it is serving. For example, I'd like to replace "this-link" with "that-link". I've tried various fastify.addHook() events listed here, https://www.fastify.io/docs/latest/Hooks/, and the sensible one to me is the "onSend" where they demonstrate [string].replace(), but all have failed. For the onSend handler, the payload is not a mutable string, but instead it appears to be a PassThrough readable stream. With that in mind, I tried inspecting the data with payload.on('data', (chunk) => {...}). That was insightful. I could see the file text, but I'm treading a bit deep into streams and fastify plugins and not sure how to proceed.

1. Is there a simple way to transform responses before they are sent when using fastify-static? (Why are the documented addHook()'s failing?)
2. Assuming I properly interpreted the payload as a readable stream, how can I transform that before fastify-static sends it?