ROS2 Humble: Shutdown causes RCLError: publisher's context is invalid

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I built some ROS2 Python nodes modeled after the ROS2 Humble demo_nodes_py/talker.py

When I run and kill a single node in my package, I get:

rclpy._rclpy_pybind11.RCLError: Failed to publish: publisher's context is invalid, at ./src/rcl/publisher.c:389

I did not have this issue running the code in ROS 2 Foxy.

The full traceback:

Traceback (most recent call last):
  File "/home/ubuntu/ros2ws/install/ros2_gopigo3_node/lib/ros2_gopigo3_node/distance_sensor", line 33, in <module>
sys.exit(load_entry_point('ros2-gopigo3-node==0.0.0', 'console_scripts', 'distance_sensor')())
File "/home/ubuntu/ros2ws/install/ros2_gopigo3_node/lib/python3.10/site-packages/ros2_gopigo3_node/distance_sensor.py", line 53, in main
    rclpy.spin(ds_node)
File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/__init__.py", line 222, in spin
executor.spin_once()
  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 712, in spin_once
raise handler.exception()
  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/task.py", line 239, in __call__
self._handler.send(None)
File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 418, in handler
await call_coroutine(entity, arg)
File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 332, in _execute_timer
await await_or_execute(tmr.callback)
File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/executors.py", line 107, in await_or_execute
return callback(*args)
File "/home/ubuntu/ros2ws/install/ros2_gopigo3_node/lib/python3.10/site-packages/ros2_gopigo3_node/distance_sensor.py", line 45, in timer_callback
self.pub.publish(self.msg_range)
File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/publisher.py", line 70, in publish
self.__publisher.publish(msg)
rclpy._rclpy_pybind11.RCLError: Failed to publish: publisher's context is invalid, at ./src/rcl/publisher.c:389
[ros2run]: Process exited with failure 1

```

It seems the only way to get rid of the error is to put a try/except pass around the publisher statement, but the demo app exits cleanly without this. Why is this happening?

Here is the code for my node:

#!/usr/bin/env python3

# File: distance_sensor.py

# Basic ROS2 Node to publish distance sensor readings

import rclpy
from rclpy.executors import ExternalShutdownException
from rclpy.node import Node

# from angles import from_degrees
from sensor_msgs.msg import Range
from di_sensors.easy_distance_sensor import EasyDistanceSensor
import math


class DistanceSensorNode(Node):

    def __init__(self):
        super().__init__('distance_sensor')
        self.ds = EasyDistanceSensor(use_mutex=True)
        self.msg_range = Range()
        self.msg_range.header.frame_id = "distance_sensor"
        self.msg_range.radiation_type = Range.INFRARED   # LASER is closer to INFRARED than ULTRASOUND
        self.msg_range.min_range = 0.0200   #         2 cm /   20 mm
        self.msg_range.max_range = 3.000    # 3 m / 300 cm / 3000 mm
        self.msg_range.field_of_view = math.radians(25.0)     # +/- 12.5 degree FOV (~60cm at max range)
        self.pub = self.create_publisher(Range, '~/distance', qos_profile=10)
        timer_period = 0.1  # 0.1 second = 10 Hz
        self.timer = self.create_timer(timer_period, self.timer_callback)
        self.get_logger().info('Created distance_sensor node at {:.0f} hz'.format(1.0/timer_period))

    def timer_callback(self):
        self.reading_mm = self.ds.read_mm()
        self.msg_range.range = self.reading_mm/1000.0
        self.msg_range.header.stamp = self.get_clock().now().to_msg ...