attempting to save R options causes C stack overflow

[kevinushey]

Sorry, but I'm not able to generate a reprex right now (it's failing with errors I don't recognize). Here's an otherwise reproducible example:

library(readr)

writeLines("a,1", con = "/tmp/test.csv")
readr::read_csv("/tmp/test.csv")

opts <- options()
save(opts, file = "/tmp/options.Rdata")

I see:

> save(opts, file = "/tmp/options.Rdata")
Error: C stack usage  7969392 is too close to the limit

This appears to be due to something funky in the cpp11_preserve_env object. (I can't inspect the cpp11_preserve_list object without seeing weird R errors)

[jimhester]

Fixed by #117