404 Route Rate Limit Configuration Throws TypeError: app.rateLimit is not a function

Prerequisites

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

Fastify version

4.27.0

Plugin version

10.0.1

Node.js version

21.7.3

Operating system

macOS

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

15.0

Description

When trying to configure rate limiting for the 404 not found handler using app.rateLimit(), the application throws a TypeError indicating that rateLimit is not a function.

Steps to Reproduce

Set up a Fastify application with @fastify/rate-limit plugin
Try to use rateLimit in setNotFoundHandler's preHandler

Code Example

import fastify from "fastify";
import rateLimit from "@fastify/rate-limit";

const app = fastify();

// Register rate limit plugin
app.register(rateLimit, {
    global: true,
    max: 1000,
    timeWindow: "1 minute"
});

// This throws TypeError: app.rateLimit is not a function
app.setNotFoundHandler(
    {
        preHandler: app.rateLimit({
            max: 10,
            timeWindow: "1 minute",
            errorResponseBuilder: (_, context) => ({
                statusCode: 429,
                error: "Too Many Requests",
                message: `Too many not found requests. Please try again in ${context.after}`
            })
        })
    },
    function (_, reply) {
        reply.code(404).send({
            statusCode: 404,
            error: "Not Found",
            message: "Route not found"
        });
    }
);

Expected Behavior The rate limit configuration should work for the 404 not found handler.

Actual Behavior Application throws TypeError: app.rateLimit is not a function

fastify / fastify-rate-limit

404 Route Rate Limit Configuration Throws TypeError: app.rateLimit is not a function #389