It generally tells you the line number of the error, either in the web browser itself or in the R session that you're serving it from. I've never had a real pr

It generally tells you the line number of the error, either in the web browser itself or in the R session that you're serving it from. I've never had a real problem with debugging the web app itself. As for debugging the R code itself, options(error=traceback) is useful (though honestly usually unnecessary) as well.