error("missing") when accessing nested value in data that was read via fjson

[philrz]

$ echo -e '{"a": {"login": "alice"}}\n{"a": null}\n{"a": {"login": "bob"}}' > data.json &&
  super -dynamic -vam -i fjson -c 'values a.login' data.json

error("missing")
error("missing")
error("missing")

Details

Repro is with super commit 6a4216d.

The query above is a simplification of the "union" query from the GitHub Archive benchmarks. I'm happy to provide repro steps with the full data set and complex query on request.

It returns the expected result with the regular JSON reader.

$ super -version
Version: v0.3.0-150-g6a4216db5

$ super -dynamic -vam -i json -c 'values a.login' data.json

"alice"
error("missing")
"bob"