slidify('index.Rmd') gives Error: is.list(val) is not TRUE

Question

I copied and pasted the Rmd from section #6 on this page http://zevross.com/blog/2014/11/19/creating-elegant-html-presentations-that-feature-r-code/ into an index.Rmd file and tried to slidify it. Results in an error. Same happens with any other example code. Is there something wrong with my solidify install?

> slidify('index.Rmd')


processing file: index.Rmd
  |................................                                 |  50%
  ordinary text without R code

  |.................................................................| 100%
label: unnamed-chunk-1 (with options) 
List of 1
 $ echo: num 5


output file: index.md

Error: is.list(val) is not TRUE
> 

Answer 1

I recently received the same error. Through trial and error, I realized that a line above the YAML front matter at the top of the slide was throwing the error (I must have accidentally added one). After deleting that line, the error stopped.

Answer 2

Have you knit the Rmd at least once already?

I had this problem and fixed it by running 'Knit HTML' first in RStudio (I'm sure there is an equivalent R command to the GUI button in RStudio) and then I ran the code:

slidify('index.Rmd')
browseURL('index.html')

My index.Rmd file is empty, so our scenarios may be different.