svelte-kit sync does not work when package file has json5 format

[christophsturm]

Describe the bug

pnpm supports json5 for the package file but when i do that 'svelte-kit sync' no longer works

Reproduction

pnpm create svelte@latest my-app # create a typescript skeletonproject with all defaults
cd my-app
mv package.json package.json5
pnpm update # to have pnpm start using json5 syntax in the file
pnpm exec svelte-kit sync
(node:23795) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
/Users/christoph/Projects/temp/my-app/svelte.config.js:1
import adapter from '@sveltejs/adapter-auto';
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at internalCompileFunction (node:internal/vm:73:18)
    at wrapSafe (node:internal/modules/cjs/loader:1166:20)
    at Module._compile (node:internal/modules/cjs/loader:1210:27)
    at Module._extensions..js (node:internal/modules/cjs/loader:1300:10)
    at Module.load (node:internal/modules/cjs/loader:1103:32)
    at Module._load (node:internal/modules/cjs/loader:942:12)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:168:29)
    at ModuleJob.run (node:internal/modules/esm/module_job:193:25)

Node.js v19.6.0

Logs

No response

System Info

System:
    OS: macOS 13.2
    CPU: (10) arm64 Apple M1 Pro
    Memory: 67.03 MB / 32.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 19.6.0 - /opt/homebrew/bin/node
    Yarn: 1.22.19 - /opt/homebrew/bin/yarn
    npm: 9.4.0 - /opt/homebrew/bin/npm
  Browsers:
    Chrome: 108.0.5359.98
    Edge: 108.0.1462.46
    Firefox Developer Edition: 107.0
    Safari: 16.3
    Safari Technology Preview: 16.4

Severity

annoyance

Additional Information

No response

[Conduitry]

pnpm may support JSON5, but Node itself still requires a package.json file with "type": "module" in order to interpret .js files as ESM. And pnpm is going to prefer the package.json file over the package.json5 file if they're both present (pnpm/pnpm#3027, pnpm/pnpm#5541). I'd suggest not using pnpm's JSON5 support for now (or even ever, maybe). There's not really anything SvelteKit can do about this for now.