title: R Markdown knit issue: "Error in -title : invalid argument to unary operator"
body: <p>Im new to R and R markdown, Im trying to run R Markdown code from a teamproject, but it doesnt run probably and I have problems understanding the errors.</p>
  <pre><code>title: &quot;R&quot;
  Error in -title : invalid argument to unary operator
  &gt; output:
  +   flexdashboard::flex_dashboard:
  +     orientation: columns
  Error: object 'output' not found
  &gt;     vertical_layout: fill
  Error: object 'vertical_layout' not found
  
  {r setup, include=FALSE}
  Error: attempt to use zero-length variable name
  library(flexdashboard)
  library(rmarkdown)
  library(knitr)
  library(readxl)
  
  Error: attempt to use zero-length variable name
   {data-width=100}
  Error in data - width = 100 : could not find function &quot;-&lt;-&quot;
  </code></pre>