title: gulp-sass, watch stops when invalid property name
body: <p>watch stops when error messages occur.</p>
  
  <pre><code>stream.js:94
        throw er; // Unhandled stream error in pipe.
              ^
  source string:51: error: invalid property name 
  </code></pre>
  
  <p>How I can keep watch running and just to tell me where is the error located.</p>
  
  <p>grunt could deal with errors and doesn't need to stop, </p>
  
  <pre><code>styleSheet.scss:41: error: invalid property name
  </code></pre>
  
  <p>otherwise, I need to keep typing "gulp" in the command-line when an error occurs.</p>