have the executor notify waitable fiddle with guard condition callbac…

…ks only if necessary

Signed-off-by: Alberto Soragna <alberto.soragna@gmail.com>

rclcpp/src/rclcpp/executors/executor_notify_waitable.cpp

@@ -152,7 +152,9 @@ ExecutorNotifyWaitable::add_guard_condition(rclcpp::GuardCondition::WeakPtr weak
  auto guard_condition = weak_guard_condition.lock();
  if (guard_condition && notify_guard_conditions_.count(weak_guard_condition) == 0) {
  notify_guard_conditions_.insert(weak_guard_condition);
- guard_condition->set_on_trigger_callback(on_ready_callback_);
+ if (on_ready_callback_) {
+ guard_condition->set_on_trigger_callback(on_ready_callback_);
+ }
  }
 }
 
@@ -163,7 +165,8 @@ ExecutorNotifyWaitable::remove_guard_condition(rclcpp::GuardCondition::WeakPtr w
  if (notify_guard_conditions_.count(weak_guard_condition) != 0) {
  notify_guard_conditions_.erase(weak_guard_condition);
  auto guard_condition = weak_guard_condition.lock();
- if (guard_condition) {
+ // If this notify waitable doesn't have an on_ready_callback, then there's nothing to unset
+ if (guard_condition && on_ready_callback_) {
  guard_condition->set_on_trigger_callback(nullptr);
  }
  }