Session aborts when debugging a function - r

Question

I have a toy function, foo, that just adds 5 to a variable x. I have a second function, n_foo that applies foo to a data.table n times. It works like so:
# Load library
library(data.table)
# Dummy function
foo <- function(x){
x + 5
}
# Apply foo n times
n_foo <- function(x, n){
Reduce(function(a, b) foo(a), 1:n, init = x)
}
# Dummy data
dt <- data.table(values = 1:10)
# Run foo 5 times
dt[, test := n_foo(.SD, 5)]
# See results
dt
#> values test
#> 1: 1 26
#> 2: 2 27
#> 3: 3 28
#> 4: 4 29
#> 5: 5 30
#> 6: 6 31
#> 7: 7 32
#> 8: 8 33
#> 9: 9 34
#> 10: 10 35
Great! Now, say something was amiss and I wanted to debug n_foo, I'd pull out the trusty debug function.
WARNING: THE FOLLOWING CODE MIGHT CRASH YOUR SESSION.
# Load library
library(data.table)
# Dummy function
foo <- function(x){
x + 5
}
# Apply foo n times
n_foo <- function(x, n){
Reduce(function(a, b) foo(a), 1:n, init = x)
}
# Dummy data
dt <- data.table(values = 1:10)
debug(n_foo)
# Run foo 5 times
dt[, test := n_foo(.SD, 5)]
# See results
dt
produces,
Curiously, the session doesn't crash if this code is run using reprex. Why does this code lead to a fatal error?
Edit:
It turns out I can only produce this issue in RStudio and not at the CLI. RStudio tag added accordingly.
R version 4.0.0 (2020-04-24)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Catalina 10.15.5
Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib
locale:
[1] en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] data.table_1.12.8
loaded via a namespace (and not attached):
[1] compiler_4.0.0 tools_4.0.0

Answer 1

no crash... but goes into debugging...
debugging in: n_foo(.SD, 5)
debug at #1: {
Reduce(function(a, b) foo(a), 1:n, init = x)
}
Browse[2]>
info
> sessionInfo()
R version 4.0.2 (2020-06-22)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 19041)
other attached packages:
[1] data.table_1.12.8
rstudio 1.3.959

Answer 2

After upgrading to RStudio v. 1.3.959, I could no longer reproduce the error.