message: viewer support invalid eval agent id
diff: @@ -282,6 +282,8 @@ 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:
  + eval_agent_ids = None
  if eval_agent_ids:
  sensed_world = world.agents[eval_agent_ids[0]].sensed_world
  if sensed_world:
  