shiny_prerendered issue: second time call says file.exists(dep$src$file) : invalid 'file'

[floswald]

i have a recurring issue with learnr tutorial that runs as a shiny app. here's the yaml

---
title: "Chapter 2 Tutorial"
output: 
  learnr::tutorial:
    highlight: pygments
    ace_theme: textmate
runtime: shiny_prerendered
---

you should be able to reproduce the error by installing my package and launching the tutorial twice. the underlying launcher is rmarkdown::run(file = rmds[1]) where rmds is a vector of filenames.

reproduce:

library(devtools)
install_github("ScPoEcon/ScPoEconometrics")
runTutorial("chapter2")  # works for me
# kill tutorial
runTutorial("chapter2")  # says 

> runTutorial("chapter2")
 Error in file.exists(dep$src$file) : invalid 'file' argument 
6.
file.exists(dep$src$file) 
5.
shiny_prerendered_prerender(input_rmd, rendered_html, output_dir, 
    encoding, prerender_option) 
4.
shiny_prerendered_html(input_rmd, encoding, render_args) 
3.
shiny_prerendered_app(target_file, encoding = encoding, render_args = render_args) 
2.
rmarkdown::run(file = rmds[1]) at runexample.R#29
1.
runTutorial("chapter2") 

[wlinInspire]

I actually have the same issue

[schloerke]

Set to be included for rmarkdown v1.13