message: fix bug viewer test
diff: @@ -284,7 +284,7 @@ class BaseViewer(Viewer):
  def drawWorld(self, world, eval_agent_ids=None, filename=None, scenario_idx=None, debug_text=True):
  sensed_world = None
  - if not eval_agent_ids[0] in world.agents:
  + if eval_agent_ids and (not eval_agent_ids[0] in world.agents):
  eval_agent_ids = None
  if eval_agent_ids:
  sensed_world = world.agents[eval_agent_ids[0]].sensed_world
  