TypeScript: svelte-kit package does not copy custom event payload types

[PuruVJ]

Describe the bug

I'm using svelte-kit package command(which is amazing BTW, kudos to you folks for it 😍). In the component, I have defined createEventDispatcher types as below 👇

const dispatch =
    createEventDispatcher<{
      start: Window;
      drag: any;
      stop: any;
      mousedown: any;
    }>();

  dispatch('start', {} as Window);
  dispatch('drag');
  dispatch('stop');
  dispatch('mousedown');

the start event has payload of type Window (just for a sample demo, final would be different). So when I run the svelte-kit package command, everything works perfectly, the svelte component is generated flaelessly, the d.ts is also perfect, with the issue that that the custom types provides for the events are stripped away, and final output has type as any

events: {
        start: any;
        drag: any;
        stop: any;
        mousedown: any;
    } & {
        [evt: string]: any;
    };

start should've had the Window type

Reproduction

Target source code: https://github.com/PuruVJ/svelte-drag/blob/e1e73f2b44abb76b3e730543a8a89b35141fa74f/src/lib/DraggableCore.svelte#L68-L74

Logs

No response

System Info

System:
    OS: Windows 10 10.0.22000
    CPU: (8) x64 Intel(R) Core(TM) i5-8265U CPU @ 1.60GHz
    Memory: 1.30 GB / 7.86 GB
  Binaries:
    Node: 14.16.1 - C:\Program Files\nodejs\node.EXE
    npm: 6.14.12 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Spartan (44.22000.1.0), Chromium (91.0.864.70)
    Internet Explorer: 11.0.22000.1
  npmPackages:
    @sveltejs/kit: ^1.0.0-next.131 => 1.0.0-next.131
    svelte: ^3.38.3 => 3.38.3

Severity

annoying

Additional Information

No response

[dummdidumm]

Is this working when using simple types like string or boolean? If so, you likely need to add DOM to the lib list in your tsconfig.json

[PuruVJ]

@dummdidumm No, not working with string, number, boolean, undefined and null and even Symbol, so I guess the prblem is with any kind of type

[dummdidumm]

You need to add DOM to the lib list in order to get the correct typings, else TS doesn't know what CustomEvent is. I updated create-svelte accordingly in #1956

[PuruVJ]

Thank you!