baseErrors property
What the base side failed on, one message each, first line only — empty when it did not fail.
On the scenario rather than only on its steps, because a failure is not
always a step: a setUpAll that throws fails every scenario in its file
before any of them captures anything, and a failing step that lines up
with nothing on the other side has no pair to carry its note.
Implementation
final List<String> baseErrors;