Unable to publish varying list of PoseStamped. gives AttributeError: 'NoneType' object has no attribute 'secs' [closed]

edit

I have created Path_arr.msg as mentioned,

string frame_id
geometry_msgs/PoseStamped[] poses

And I want to publish next 5 states of robot that should be subscribed by other local in range robots, for That I have code as below. All other part of code runs good so I am posting only necessary part of code.

next5_pub = rospy.Publisher(('/'+robot.ns+'/next5'), Path_arr, queue_size=10) 
next5 = Path_arr()
next5.frame_id = robot.ns
on_goal = False
rate = rospy.Rate(5)

i = 0
while not rospy.is_shutdown() and not on_goal:
  # path is array of PoseStamped
  pose = path[i]
  # Move the robot
  if not on_goal:
    linear_goal(pose, robot, mapInfo,on_goal=on_goal)
  if pose.header.frame_id == robot.goal.header.frame_id:
    on_goal=True
  # collect next 5 pose from path to publish 
  if len(path)-path.index(pose) <6 :
    adding = len(path)-path.index(pose)
    path.extend([path[-1]]*adding)
  next5.poses = path[path.index(pose)+1:path.index(pose)+6]
  i+=1
  next5_pub.publish(next5)
  rate.sleep()

While running this node It doesn't give any error. Even rostopic list has topic named /waffle1/next5. But when I try to subscribe to the topic. It crash the node and give the following error.

Traceback (most recent call last):
File "/home/user/ros/src/path_planning/scripts/algo1.py", line 128, in <module>
next5_pub.publish(next5)
File "/opt/ros/noetic/lib/python3/dist-packages/rospy/topics.py", line 882, in publish
self.impl.publish(data)
File "/opt/ros/noetic/lib/python3/dist-packages/rospy/topics.py", line 1066, in publish
serialize_message(b, self.seq, message)
 File "/opt/ros/noetic/lib/python3/dist-packages/rospy/msg.py", line 152, in serialize_message
msg.serialize(b)
File "/home/user/ros/devel/lib/python3/dist-packages/path_planning/msg/_Path_arr.py", line 117, in serialize
buff.write(_get_struct_2I().pack(_x.secs, _x.nsecs))
AttributeError: 'NoneType' object has no attribute 'secs'

At first I had doubt that I might not have datatype of PoseStamped in variable path. But after checking the type of elements in the path I confirm it is PoseStamped

type(path[0])
<class 'geometry_msgs.msg._PoseStamped.PoseStamped'>

On other side When I try to publish static array from outside the while loop, It doesn't give error while subscribing. I am not sure what error I am making here.

Thank you.