Solution
Each TS step has a Result container that itself contains an Error container.
In that error container you have similar to the LabVIEW cluster, a numeric Code element, a string element Msg and a boolean Occurred.
If the boolean is true, TS will raise the error to the user with the Msg shown as the error description in the run-time error dialog and in the UUT resuts.
Ideally, the source that generates the error would set Msg accordingly but you can set or change this element as well.
For example if you have some expression that triggers an error, set Step.Result.Error.Msg to the error message you want to have displayed.
