Fix start_type_description_service param handling (backport #2897)

[mergify]

Closes #2892 by using the same exact strategy for declaring use_sim_time.

rclcpp/rclcpp/src/rclcpp/time_source.cpp

Lines 254 to 274 in 7ebc9e4

	rclcpp::ParameterValue use_sim_time_param;
	const std::string use_sim_time_name = "use_sim_time";
	if (!node_parameters_->has_parameter(use_sim_time_name)) {
	use_sim_time_param = node_parameters_->declare_parameter(
	use_sim_time_name,
	rclcpp::ParameterValue(false));
	} else {
	use_sim_time_param = node_parameters_->get_parameter(use_sim_time_name).get_parameter_value();
	}
	if (use_sim_time_param.get_type() == rclcpp::PARAMETER_BOOL) {
	if (use_sim_time_param.get<bool>()) {
	parameter_state_ = SET_TRUE;
	clocks_state_.enable_ros_time();
	create_clock_sub();
	}
	} else {
	RCLCPP_ERROR(
	logger_, "Invalid type '%s' for parameter 'use_sim_time', should be 'bool'",
	rclcpp::to_string(use_sim_time_param.get_type()).c_str());
	throw std::invalid_argument("Invalid type for parameter 'use_sim_time', should be 'bool'");
	}

Tested (you can try to define start_type_description_service like so, and pass it to Nav2 bt_navigator or diagnostic_aggregator):

/**:
  ros__parameters:
    use_sim_time: false
    start_type_description_service: false

whithout the patch, it crashes like ros/diagnostics#519.

• Add test

Did you use Generative AI?

No

---

This is an automatic backport of pull request #2897 done by Mergify.

[fujitatomoya]

Pulls: #2909
Gist: https://gist.githubusercontent.com/fujitatomoya/da08f6083dcc62564b8edd80a60aa9ff/raw/b82e7ce0ae942e1e5dde8cb2ea389a18de288671/ros2.repos
BUILD args: --packages-above-and-dependencies rclcpp
TEST args: --packages-above rclcpp
ROS Distro: jazzy
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/16509

• Linux
• Linux-aarch64
• Linux-rhel
• Windows