Typescript for +layout.svelte should not give ok to PageData

[simonh1000]

Describe the bug

I had misunderstood the docs and created a +page.ts and a +layout.svelte.

In the latter I had export let data: PageData;

which vsCode said was ok and would give me the data I expected. But the runtime does not pass data this way - you need +layout.ts to get data for +layout.svelte

Reproduction

create a +page.ts that returns {user: Promise.resolve(user)}

and a +layout.svelte with

export let data: PageData;
const user : User = data.user;
console.log(data.user)

line 2 is wrongly Oked by typescript

Logs

logs `undefined`

System Info

System:
    OS: macOS 13.1
    CPU: (8) x64 Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
    Memory: 28.33 MB / 8.00 GB
    Shell: 5.8 - /usr/local/bin/zsh
  Binaries:
    Node: 16.16.0 - ~/.nvm/versions/node/v16.16.0/bin/node
    npm: 8.11.0 - ~/.nvm/versions/node/v16.16.0/bin/npm
  Browsers:
    Chrome: 108.0.5359.124
    Firefox: 104.0.2
    Safari: 16.2
    Safari Technology Preview: 16.4
  npmPackages:
    @sveltejs/adapter-auto: ^1.0.0 => 1.0.0 
    @sveltejs/kit: ^1.0.0 => 1.0.0 
    svelte: ^3.54.0 => 3.55.0 
    vite: ^4.0.0 => 4.0.1

Severity

serious, but I can work around it

Additional Information

No response