understand geterrmessage() vs toString(result)

[jonathancallahan]

Jon has discovered that the text in stop() messages isn't always available from geterrmessage(). It appears that, in the context of result <- try({ ...}), friendly error messages generated by Mazama validation code is available from toString(result).

We should understand this difference and adjust MazamaCoreUtils::stopOnError() to present the best available information.