Can someone enlighten me, I cannot get my head around rendering Rmarkdown scripts via nextflow:

#! /usr/bin/env nextflow

nextflow.enable.dsl=2

process renderRMD {

    input:
    path(rmd)

    output:
    path("script.html")
    path("out.txt")

    script:
    """

    ## this works fine and gets emitted to the work dir
    Rscript -e 'write.table(x=data.frame(A=1), file="out.txt")' 

    ## this causes an error
    script -e 'rmarkdown::render("${rmd}", output_file="script.html")'

    ## and also this:
    Rscript -e 'rmarkdown::render("${rmd}", output_file="$workDir/script.html")'

    """

} 

workflow { renderRMD( Channel.fromPath("${baseDir}/script.rmd") ) }

This always exits with error:

Caused by:
  Missing output file(s) `script.html` expected by process `renderRMD (1)`

The out.txt file gets properly emitted to the work directory, but this Rmarkdown html causes an error. The html in fact is created to the same directory as the script.rmd file is located in, but for a reason I do not understand it does not get emitted to the work dir, hence nextflow "does not know about it" and this raises the error about the missing file.

Let script.rmd just be:

---
title: "nf-render"
output:
  html_document: default
---

```{r,eval=TRUE,echo=TRUE}

library(ggplot2)
ggplot(cars, aes(speed,dist)) + geom_point()

```

Any ideas?