Fix JSON file error handling

[pratyushsinghal7]

Fixes #1314

Summary

• pass JSON file-loading failures to the query error callback
• route malformed JSON parse failures through the same error path
• add regression coverage for callbacks and lazy promises

Testing

• bun test --preload ./test/bun-setup.js ./test/test1314.js (3 passed)
• bun run test-only (2191 passed, 213 skipped, 0 failed)
• bun x prettier --check src/84from.js test/test1314.js

[mathiasrw]

Very smooth. Thank you!

[mathiasrw]

As it might break existing functionality we will merge it on next major version bump