docs: function formatSassError(err, data) {
    // Generate three-line preview around the error:
    var preview = data.split('\n');
    preview = preview.slice(Math.max(0, err.line-2), Math.min(err.line+1, preview.length-1));
    preview = preview.map(function(src) { return '>>> '+ src });
    preview.unshift(err.message);
  
    var error = new Error('Error rendering theme Sass:\n'+ preview.join('\n'));
    error.line = err.line || null;
    error.column = err.column || null;
    return error;
  }