fix: allow empty-string JSON keys when checking duplicate keys

[SergioChan]

Summary

• avoid rejecting valid JSON files that use an empty string ("") object key
• keep duplicate-key protection in place, but ignore the known false-positive parser error (Syntax error: empty string near)
• add a regression test fixture and CLI test coverage for this case

Testing

• npx jest test/cli-validator/tests/error-handling.test.js --runInBand (from packages/validator)

Related

• Fixes Syntax error: empty string near e": {"": " #513

[CLAassistant]

All committers have signed the CLA.

[SergioChan]

Thanks for the check. I’ll rewrite the branch with signed-off commits so the DCO gate passes, then push an updated commit set.

[SergioChan]

Update pushed ✅ I rebased the branch with --signoff and force-pushed, so all commits now carry Signed-off-by lines for DCO.