Rewatch: panic when "name" field is missing in package.json

[cknitt]

There is tests/package_tests/installation_test/rescript.json, but no matching package.json.

The package.json is created by npm i --no-audit rescript@... in ci.yml and does not contain a "name" field.

thread 'main' (83708) panicked at src/build/packages.rs:483:56:
Could not read package name: No name field found in package.json

see https://github.com/rescript-lang/rescript/actions/runs/21092139422/job/60665084960?pr=8183