Error on wrong custom output in interactive problem is confusing

[kunyavskiy]

The error sais

StatementProcessException: com.codeforces.polygon.statement.StatementProcessException: Output for statements doesn't give OK while judging: tests/1.

It's totally unclear what was tested. Was it your custom output submitted to the interactor? Was it output treated as the output of the interactor to check? How custom input is handled here?

Because of this unclarity, it's very easy to say, "Meh, it checked something strange. Let me just disable it". While it seams to be checking something meaningful at least in some cases.