svelte-kit sync doesn't run everytime on postinstall for pnpm

[brian14708]

Describe the bug

After following the instruction

`svelte-kit sync` now runs on "postinstall" — please remove the "prepare" script from your package.json

Sometimes pnpm run check fails in a clean workspace (git clean / CI).

I believe it has something to do with pnpm's side-effects-cache. It seems to fixed after disabling side-effects-cache in .npmrc

Reproduction

npm create svelte@latest test-postinstall
cd test-postinstall
pnpm i
rm -rf node_modules .svelte-kit
pnpm i
## no .svelte-kit folder
pnpm run check ## <-- FAIL

Logs

No response

System Info

npmPackages:
    @sveltejs/adapter-auto: next => 1.0.0-next.64 
    @sveltejs/kit: next => 1.0.0-next.401 
    svelte: ^3.46.0 => 3.49.0 
    vite: ^3.0.0 => 3.0.4

Severity

serious, but I can work around it

Additional Information

No response

[dominikg]

There are two issues on pnpm repo related to this:

1. Adding more variables to the side-effects-cache key pnpm/pnpm#5002
2. Add option to re-run dependency scripts (install/postinstall) pnpm/pnpm#1394

Disabling the side-effects-cache globally in users projects may result in extra work.
Alternative / workaround would be to ensure that sync is run before check aswell, either by prepending it to the created script: "check":"svelte-kit sync && ... or by check itself inspecting the project and calling sync if it is svelte-kit.

[Rich-Harris]

The solution here is to run svelte-kit sync before check, as happens for new projects after #6037 and #6339