Adding traceback() info

[HeidiSeibold]

I asked a question about whether to add traceback-output during the ROpenSci community call and @jennybc asked me to open an issue. So here it is 🍰

What I imagine could look like the sessionInfo() tab, that one can open if they want to.
I.e. something like reprex::reprex(rnorm(10), venue = "gh", si = TRUE, tb = TRUE) where additionally to the session-info-tab there will also appear a traceback-tab.

The question came to me because I was asked to add the traceback in an issue I recently opened: mlr-org/mlr#1490

[hadley]

I think reprex should probably add the traceback() by default by using a custom error handler

[hadley]

Actually this is more challenging than I thought because reprex uses rmarkdown/knitr, which eats errors in an internal tryCatch().

[wlandau]

For what it's worth, I have started using evaluate::try_capture_stack() as a temporary workaround.

code <- quote(identity(stop("msg")))
env <- environment()
error <- evaluate::try_capture_stack(code, env)
error$message
#> [1] "msg"
error$call
#> identity(stop("msg"))
error$calls
#> [[1]]
#> identity(stop("msg"))
#> 
#> [[2]]
#> stop("msg")

^{Created on 2019-03-15 by the reprex package (v0.2.1)}

[jennybc]

I suspect the long-term solution to this is going to be #230 Entrace base errors?

[jennybc]

Closing with the rationale that #230 represents the improvements needed.