title: Effectively debugging Shiny apps
body: <p>I have a complex Shiny app spread across multiple files that uses code from several packages. The app works when run locally in R Studio, but on my server it throws a generic error: </p>
  
  <blockquote>
    <p>Error: do not know how to convert 'x' to class "Date"</p>
  </blockquote>
  
  <p>This is probably a simple programming mistake, but figuring out exactly <em>where</em> that mistake is in the code is proving difficult. </p>
  
  <p>How can I hunt down and fix the source of errors in Shiny apps? And what tools are available to do this in a systematic way? </p>
  
  <hr>
  
  <p>There has been some discussion of similar problems on <a href="https://groups.google.com/forum/#!topic/shiny-discuss/M4yy0pZMx_s" rel="noreferrer">Google Groups</a>. </p>