Capturing warnings/rejects from rstan with multiple cores

So I would like to capture, process and relay the warning messages that happen during model fitting. I must be missing something basic as I was not able to do this. I can do this in cmdstanr, but I want to fully support rstan in the SBC package.

e.g. when running:


model_code <- "

parameters {
  real mu;

model {
  mu ~ lognormal(0,5);

m <- stan_model(model_code = model_code)

sampling(m, chains = 4, cores = 1)

I get something like:

Chain 2: Rejecting initial value:
Chain 2:   Error evaluating the log probability at the initial value.
Chain 2: Exception: lognormal_lpdf: Random variable is -0.825686, but must be nonnegative! (in 'string', line 5, column 2 to column 22)

.... (lots of ther stuff)

But when running

sampling(m, chains = 4, cores = 4)

the messages only ever appear in the Viewer pane of Rstudio. I figured out I can disable the viewer pane by calling Sys.setenv("RSTUDIO" = "0") before sampling (which is less than ideal, but I can live with this), however, even after disabling the viewer, the progress + warning messages are not shown anywhere…

I am using rstan 2.26.3

Maybe @jonah would know?