This also applies to other functions, such as resolve in Handle. I created an issue in the svelte repo for it, but it obviously belongs here in the kit repo.

Just posting the relevant details here, as it is the exact same issue as the OP is describing.

Describe the bug

When destructuring a function out of a function argument, for example like this:

// `resolve` is a function that is destructured out of the function argument
async function handle({ event, resolve }) {
  // ...
}

ESLint yells at me:

error  Avoid referencing unbound methods which may cause unintentional scoping of `this`.
If your function does not access `this`, you can annotate it with `this: void`, or consider using an arrow function instead  @typescript-eslint/unbound-method

Destructuing the function argument is very common, and is the way it's done in both the Docs and Tutorial for the handle hook.

I don't think resolve uses this, so I think the issue would be solved by declaring Handle like this (using arrow function for resolve):

export type Handle = (input: {
  event: RequestEvent;
  resolve: (event: RequestEvent, opts?: ResolveOptions) => MaybePromise<Response>;
}) => MaybePromise<Response>;

or this (annotating resolve with this: void):

export type Handle = (input: {
  event: RequestEvent;
  resolve(this: void, event: RequestEvent, opts?: ResolveOptions): MaybePromise<Response>;
}) => MaybePromise<Response>;

instead of this (resolve is a regular function):

export type Handle = (input: {
  event: RequestEvent;
  resolve(event: RequestEvent, opts?: ResolveOptions): MaybePromise<Response>;
}) => MaybePromise<Response>;

Note: The same issue applies to some other functions. At least parent in LayoutLoad and PageLoad comes to mind.

Reproduction

Set up SvelteKit with ESLint and @typescript-eslint/recommended-type-checked.

Set up a handle hook:

// src/hooks.server.js
import type { Handle } from "@sveltejs/kit";

export const handle: Handle = async ({ event, resolve }) => {
  return await resolve(event);
}

This is strange because those functions are arrow functions although it reports otherwise. Adding the this: void annotation in public.d.ts and turning it into an arrow function doesn't help either.

This is strange because those functions are arrow functions although it reports otherwise. Adding the this: void annotation in public.d.ts and turning it into an arrow function doesn't help either.

Strange indeed! I also did a little test making changes to public.d.ts inside the node_modules folder of my project without getting it to work 🤔

Any idea who might be able to look into this, @eltigerchino?

Any idea who might be able to look into this, @eltigerchino?

Not at the moment. The team is still busy with the post-launch of Svelte 5.