Missing dependency in R Studio/Preventing pdf output

[RobinL]

To reproduce:

File -> New Project -> R Markdown -> Knit -> to pdf

error message:

/usr/lib/rstudio-server/bin/pandoc/pandoc +RTS -K512m -RTS a.utf8.md --to latex --from markdown+autolink_bare_uris+ascii_identifiers+tex_math_single_backslash --output a.pdf --template /usr/local/lib/R/site-library/rmarkdown/rmd/latex/default-1.17.0.2.tex --highlight-style tango --latex-engine pdflatex --variable graphics=yes --variable 'geometry:margin=1in' 
output file: a.knit.md

! LaTeX Error: File `lmodern.sty' not found.

Type X to quit or <RETURN> to proceed,
or enter new name. (Default extension: sty)

Enter file name: 
! Emergency stop.
<read *> 

l.3 \usepackage

pandoc: Error producing PDF
Error: pandoc document conversion failed with error 43
Execution halted

[andyhd]

I've reproduced this error

[andyhd]

I've added the lmodern package to the default RStudio image. This fixes the problem on my RStudio instance after I redeployed it.