message: bug fix if no labels
diff: @@ -278,9 +278,9 @@ class BaseViewer(Viewer):
  if isinstance(observed_world.evaluators[evaluator_type], EvaluatorLTL):
  label_functions = observed_world.evaluators[evaluator_type].label_functions
  # we will only plot labels of first ltl evaluator
  + self.drawLabelsAsText(observed_world, label_functions, evaluator_type)
  break
  - self.drawLabelsAsText(observed_world, label_functions, evaluator_type)
  def drawMap(self, map):
  # draw the boundary of each lane
  