Plot does not produce any output in Julia chunks when used in bookdown documents

[Woidboy]

I'd like to generate Julia plots for a book written with bookdown. The following code

```{julia, dev='png'}
using Plots
gr()
plot(1:10,1:10)

produces the following error:

GKS: file open error (/tmp.pdf)
open: Keine Berechtigung (german for no permission)

Why is there a PDF-File involved although the output file format has been selected to be PNG?

I'm using Julia 1.5.3, R version 3.6.3, and JuliCall 0.17.1.

[LafageDenis]

Hi,

I am facing the same issue with Julia 1.7 and 1.8 and JuliaCall 0.17.4 under R 4.1.2. on Ubuntu.