Uninformative error if session terminates

[hadley]

# devtools::install_github("romainfrancois/trump")

callr::r(function() library(trump))
#> Error in readRDS(res) : error reading from connection 
#> 3. readRDS(res) 
#> 2. get_result(output = out, options) 
#> 1. callr::r(function() library(trump)) 

[gaborcsardi]

This is "fixed" in R-devel, the problem is that saveRDS creates an output file, even if it fails. So on R-devel you get "child process crashed or was killed".

We can work around this, and assume that if the RDS file is corrupt, then the R process probably crashed.