fix(node): return an error instead of panicking on a zero-field JSON schema

[phil-opp]

Issue

read_json_value_as_arrow (apis/rust/node/src/daemon_connection/json_to_arrow.rs) ended with:

Ok(batch.column(0).to_data())

RecordBatch::column(0) indexes out of bounds and panics when the batch has no columns. This is a pub fn whose schema is caller-supplied, and a zero-field schema is reachable: the node integration-testing harness (node_integration_testing.rs) builds the schema via infer_json_schema_from_iterator(...) when no data_type is given, and an empty JSON array infers a schema with no fields. That degenerate-but-valid input turns into a panic instead of a recoverable error. (The sibling read_from_json_with_schema is unaffected — its wrapped() always injects an "inner" field, guaranteeing ≥1 column.)

Fix

Use batch.columns().first().context(...)? so a zero-column batch returns an eyre::Result error rather than panicking:

Ok(batch
    .columns()
    .first()
    .context("JSON record batch has no columns")?
    .to_data())

Validation

cargo test -p dora-node-api --lib json_to_arrow    # 2 passed (new)
cargo clippy -p dora-node-api -- -D warnings
cargo fmt --all -- --check

New unit tests cover: a zero-field schema returns Err (no panic), and a normal single-field schema still round-trips.

---

⚠️ This is a machine-generated PR authored by Claude (Claude Code) as part of an automated codebase review. The finding was verified by hand against origin/main before opening. Please review carefully before merging.

🤖 Generated with Claude Code

---

Generated by Claude Code

[trunk-io]

Merging to main in this repository is managed by Trunk.

• To merge this pull request, check the box to the left or comment /trunk merge below.

After your PR is submitted to the merge queue, this comment will be automatically updated with its status. If the PR fails, failure details will also be posted here

[phil-opp]

🤖 Automated review by Claude — this is a fully automated review with no human in the loop. Treat it as advisory.

Reviewed the diff — no issues found. Swapping batch.column(0) for a shared first_column_data helper backed by columns().first() correctly removes the out-of-bounds panic on a zero-column batch, and both JSON→Arrow call sites are updated.

Minor test note: empty_schema_returns_err_not_panic asserts only is_err(), and a zero-field schema may already short-circuit earlier at the "no record batch in JSON" context before ever reaching first_column_data — so it validates the overall no-panic contract but doesn't guarantee the new helper is the branch actually exercised. If the intent is to pin the new helper specifically, constructing a batch that has a record but zero columns would target it directly. The single-field round-trip test is solid.

---

Generated by Claude Code