Rstudio Server crashes when using callr::r

Hello!

Issue history

tried to migrate a targets workflow to an Rstudio Server Open Source Edition and everytime I try to run any make related command, e.g targets::tar_make() or targets::tar_visnetwork()the R Session in the Server crashes.

Identified problem

I could winnow the issue down to callr::r which is used by targets to instantiate separate R processes.

The issue can be reproduced with

library(callr)
callr::r(function() var(iris[, 1:4]))

leading to a crash.

My question: Is this expected behaviour as Rstudio Server Open Source Edition states that it can only run one R process or should I go hunting for a genuine error?

If so any ideas?

Thank you very much!

Session Info

platform       x86_64-suse-linux-gnu       
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          4                           
minor          1.0                         
year           2021                        
month          05                          
day            18                          
svn rev        80317                       
language       R                           
version.string R version 4.1.0 (2021-05-18)
nickname       Camp Pontanezen