Not found handler not called when used as plugin with prefix

[vlatkoodrljin]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.4.0

Plugin version

6.5.0

Node.js version

16.14.2

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

12.5

Description

I need to serve static files from several sibling directories, every directory on different route.

Wrapped this plugin in a plugin with prefix which seems valid to me.

When path is correct everything works ok.

Cannot use 404 handler properly, and that makes everything confusing and pretty unreliable.

If path is not correct not found handler is not called and following error is occurred:

TypeError: Cannot read properties of undefined (reading 'length') at next (fastify-static-not-found-bug/node_modules/fastify/lib/hooks.js:212:25) at onSendHookRunner (fastify-static-not-found-bug/node_modules/fastify/lib/hooks.js:241:3) at preserializeHook (fastify-static-not-found-bug/node_modules/fastify/lib/reply.js:454:5) at _Reply.Reply.send (fastify-static-not-found-bug/node_modules/fastify/lib/reply.js:182:7) at fastify-static-not-found-bug/node_modules/fastify/lib/wrapThenable.js:25:15

Not sure if this is related with encapsulation in some way, but I think that according to the docs everything is valid.

Steps to Reproduce

https://github.com/vlatkoodrljin/fastify-static-not-found-bug

yarn install

node index

Visit for example: http://localhost:3000/public/js/temp2.js and observe returned error

Expected Behavior

Calling of proper not found handler defined in specific plugin context.