The discussion you are describing should have occurred while developing a spec.

What is said in the spec specifically about that "error" or at least in general about interface errors? The idea is to test to an a spec agreed to prior to beginning the implementation. The spec is the contract between the developer and the user.

If the spec says nothing, you've got one poor spec and never ending problems are resolved in a pissing contest. That's how you blow schedules and costs estimates.

Otherwise, error numbers require that you look them up in a manual which may not be handy. Software interfaces use error numbers, not people.