message: Linting the DTR color filter.
diff: @@ -214,7 +214,7 @@ mod.filter('qualityColor', function() {
  mod.filter('dtrRatingColor', function() {
  return function getColor(value, property) {
  if (!value) {
  - return;
  + return null;
  }
  property = property || 'background-color';
  @@ -236,7 +236,7 @@ mod.filter('dtrRatingColor', function() {
  result[property] = 'hsl(' + color + ',85%,60%)';
  return result;
  };
  -})
  +});
  /**
  * Reduce a string to its first letter.
  