title: How (or why) does commented out code in Javascript cause a HTML template to error when rendering?
body: <p>I'm creating an application using Flask, so the usual suspects on the Client Side and Python on the Server Side.</p>
  
  <p>While adding in some new functionality via new JavaScript code in the SCRIPT section, one of my templates started to error when rendering. When I commented out this new code, the error continued to occur.</p>
  
  <p>Thinking I'd maybe made a mistake on the Python side, I commented out all the new code relating to the most recent change, but the error persisted. The error I received was:</p>
  
  <blockquote>
    <p>Internal Server Error</p>
    
    <p>The server encountered an internal error and was unable to complete
    your request. Either the server is overloaded or there is an error in
    the application.</p>
  </blockquote>
  
  <p>It turns out that one single line of JavaScript code was causing this rendering error. Commenting it out made no difference - I had to remove it completely before my template would render correctly.</p>
  
  <p>Has anyone ever encountered this before? It goes against everything I've ever seen in the past 20 years as a professional coder! The line of code causing the error is exactly below.</p>
  
  <p>If I paste this line into any of the other HTML templates in my application, then those templates will not render either.</p>
  
  <p>Not only can I not see a valid reason for the template to error (by which I mean, the code is valid and should run), I'd really love to know if anyone has experienced this phenomenon too, where commented out code can cause an error when rendering a template?</p>
  
  <p>I've already "fixed" the issue by renaming the variables, but how on earth can such a line cause a rendering error? Any help or ideas or similar experiences would be most welcome.</p>
  
  <p>For info, I'm using Microsoft Visual Studio (the latest free version) to develop this application.</p>
  
  <pre><code>//var JSONarrayOfWords = {{ JSON_allRowsForSpecificLanguage| tojson}};     //populate a JSON array from the (jinja?) FLASK array (originally a LIST in python)
  </code></pre>