type of FetchEvent.handled shold be Promise<undefined> not Promise<void>;

[yhonda-ohishi]

https://github.com/microsoft/TypeScript/blob/main/src/lib/webworker.generated.d.ts#L3245C23-L3246C1
https://w3c.github.io/ServiceWorker/#fetchevent

[MartinJohns]

This is working as intended. The return value of the promise is nothing that's really used, it makes no sense to have it typed undefined instead of void. I'd even say it would be worse, because having a real return type should make the user evaluate the returned value, whereas with void it's clear that it doesn't need to be checked.

[yhonda-ohishi]

using hono,service-worker handler,
https://github.com/honojs/hono/blob/e0f8dd83fb8b84b1a28dee087c50693263fefde6/src/adapter/service-worker/handler.ts#L4
https://hono.dev/docs/getting-started/service-worker

getting the error bellow in vscode

No overload matches this call.
  Overload 1 of 2, '(type: "fetch", listener: (this: ServiceWorkerGlobalScope, ev: FetchEvent) => any, options?: boolean | AddEventListenerOptions | undefined): void', gave the following error.
    Argument of type 'Handler' is not assignable to parameter of type '(this: ServiceWorkerGlobalScope, ev: FetchEvent) => any'.
      Types of parameters 'evt' and 'ev' are incompatible.
        Type 'FetchEvent' is not assignable to type 'import("/workspace/nuxt-ble-test/node_modules/hono/dist/types/adapter/service-worker/types").FetchEvent'.
          Types of property 'handled' are incompatible.
            Type 'Promise<void>' is not assignable to type 'Promise<undefined>'.
              Type 'void' is not assignable to type 'undefined'.
  Overload 2 of 2, '(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void', gave the following error.
    Argument of type 'Handler' is not assignable to parameter of type 'EventListenerOrEventListenerObject'.
      Type 'Handler' is not assignable to type 'EventListener'.
        Types of parameters 'evt' and 'evt' are incompatible.
          Type 'Event' is missing the following properties from type 'FetchEvent': clientId, handled, preloadResponse, request, and 3 more.

acording source
hono's FetchEvent interface is like

export interface FetchEvent extends ExtendableEvent {
  readonly clientId: string
  readonly handled: Promise<undefined>
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  readonly preloadResponse: Promise<any>
  readonly request: Request
  readonly resultingClientId: string
  respondWith(r: Response | PromiseLike<Response>): void
}

if its intentional, shudo i just do // @ts-ignore?

[typescript-bot]

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