`+layout.server.ts` not re-running after slug change

[HegarGarcia]

Describe the bug

When changing slug in a route, the +page.server.ts gets called but the +layout.server.ts doesn't event though in depends on the params.

GIven a url structure: /foo/[baz].

When going from /foo to /foo/abc:

• foo/[baz]/+layout@.server.ts#load doesn't run
• if a foo/+page.server.ts exists, then foo/[slug]/+page.svelte will receive it's return value

When going from /foo to /foo/abc to /foo/xyz:

• foo/[baz]/+layout@.server.ts#load doesn't get executed
• if a foo/+page.server.ts exists, then foo/[slug]/+page.svelte will receive the same props no matter how many slug changes are performed

When accessing directly /foo/abc

• foo/[baz]/+layout@.server.ts#load gets executed

When accessing directly /foo/abc then go the /foo/xyz

• foo/[baz]/+layout@.server.ts#load gets executed on /foo/abc
• foo/[baz]/+layout@.server.ts#load doesn't get executed when routing to /foo/xyz

This happens no matter if you are using <a> or the goto function.

Reproduction

Reproduction

From the landing page, follow the link between the pages and see the output of each page.

Logs

No response

System Info

System:
  OS: macOS 12.5.1
  CPU: (8) arm64 Apple M1
  Memory: 224.58 MB / 16.00 GB
  Shell: 5.8.1 - /bin/zsh
Binaries:
  Node: 16.16.0 - ~/.nvm/versions/node/v16.16.0/bin/node
  Yarn: 1.22.15 - ~/.nvm/versions/node/v16.16.0/bin/yarn
  npm: 8.11.0 - ~/.nvm/versions/node/v16.16.0/bin/npm
Browsers:
  Chrome: 104.0.5112.101
  Safari: 15.6.1
npmPackages:
  @sveltejs/adapter-auto: next => 1.0.0-next.66 
  @sveltejs/kit: 1.0.0-next.436 => 1.0.0-next.436 
  svelte: ^3.44.0 => 3.49.0 
  vite: ^3.0.8 => 3.0.8

Severity

serious, but I can work around it

Additional Information

No response

[HegarGarcia]

Adding the /foo/[slug]/+page.server.ts file, completely empty, solves the issue.

To remove the isolatedModules error just add export {};

---

You can even create an empty load function and will still work.

Had to manually add the return type so that PageData interface can infer the types correctly.

If any value is returned, it follows normal behavior; gets merge with return value of /foo/[slug]/+layout.server.ts.

import type { PageServerLoad } from './$types';
import type { load as layoutLoad } from './+layout.server';

export const load: PageServerLoad = async (): Promise<ReturnType<typeof layoutLoad>> => {
	return;

	// return { test: 'foo' };
};

If you try to await parent() inside the function you get the following error #6255

Cannot read properties of null (reading 'data')
TypeError: Cannot read properties of null (reading 'data')
    at parent (file:///node_modules/.pnpm/@sveltejs+kit@1.0.0-next.436_svelte@3.49.0+vite@3.0.8/node_modules/@sveltejs/kit/src/runtime/server/index.js:288:41)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async load (/src/routes/foo/[slug]/+page.server.ts:5:1)
    at async load_server_data (file:///node_modules/.pnpm/@sveltejs+kit@1.0.0-next.436_svelte@3.49.0+vite@3.0.8/node_modules/@sveltejs/kit/src/runtime/server/page/load_data.js:38:17)
    at async Promise.all (index 2)
    at async resolve (file:///node_modules/.pnpm/@sveltejs+kit@1.0.0-next.436_svelte@3.49.0+vite@3.0.8/node_modules/@sveltejs/kit/src/runtime/server/index.js:311:22)
    at async respond (file:///node_modules/.pnpm/@sveltejs+kit@1.0.0-next.436_svelte@3.49.0+vite@3.0.8/node_modules/@sveltejs/kit/src/runtime/server/index.js:216:20)
    at async file:///node_modules/.pnpm/@sveltejs+kit@1.0.0-next.436_svelte@3.49.0+vite@3.0.8/node_modules/@sveltejs/kit/src/vite/dev/index.js:375:22