fix(multi_object_tracker): fix segmentation fault bug of the debug object process

[technolojin]

Description

In the planning simulator, the multi-object-tracker crash was reported.
#7127 (comment)

[multi_object_tracker_node-49] *** Aborted at 1717082878 (unix time) try "date -d @1717082878" if you are using GNU date ***
[multi_object_tracker_node-49] PC: @                0x0 (unknown)
[multi_object_tracker_node-49] *** SIGSEGV (@0x20) received by PID 461172 (TID 0x7df1e7c2f8c0) from PID 32; stack trace: ***
[multi_object_tracker_node-49]     @     0x7df1e548a206 (unknown)
[multi_object_tracker_node-49]     @     0x7df1e7a45320 (unknown)
[multi_object_tracker_node-49]     @     0x7df1e4932f0f TrackerObjectDebugger::process()
[multi_object_tracker_node-49]     @     0x7df1e48f8e08 TrackerDebugger::publishObjectsMarkers()
[multi_object_tracker_node-49]     @     0x7df1e48881e6 multi_object_tracker::MultiObjectTracker::publish()
[multi_object_tracker_node-49]     @     0x7df1e4887e5e multi_object_tracker::MultiObjectTracker::checkAndPublish()
[multi_object_tracker_node-49]     @     0x7df1e48875cc multi_object_tracker::MultiObjectTracker::onTimer()
[multi_object_tracker_node-49]     @     0x7df1e48cf76d std::__invoke_impl<>()
[multi_object_tracker_node-49]     @     0x7df1e48c98e9 std::__invoke<>()
[multi_object_tracker_node-49]     @     0x7df1e48c449b _ZNSt5_BindIFMN20multi_object_tracker18MultiObjectTrackerEFvvEPS1_EE6__callIvJEJLm0EEEET_OSt5tupleIJDpT0_EESt12_Index_tupleIJXspT1_EEE
[multi_object_tracker_node-49]     @     0x7df1e48bdab5 std::_Bind<>::operator()<>()
[multi_object_tracker_node-49]     @     0x7df1e48edabc rclcpp::GenericTimer<>::execute_callback_delegate<>()
[multi_object_tracker_node-49]     @     0x7df1e48ea877 rclcpp::GenericTimer<>::execute_callback()
[multi_object_tracker_node-49]     @     0x7df1e8307a51 rclcpp::Executor::execute_any_executable()
[multi_object_tracker_node-49]     @     0x7df1e8319234 rclcpp::executors::SingleThreadedExecutor::spin()
[multi_object_tracker_node-49]     @     0x65224930e45c main
[multi_object_tracker_node-49]     @     0x7df1e7a2a1ca (unknown)
[multi_object_tracker_node-49]     @     0x7df1e7a2a28b __libc_start_main
[multi_object_tracker_node-49]     @     0x65224930dac5 _start

The code was reviewed and found a bug can cause segmentation fault.

Tests performed

The symptom couldn't be reproduced in my environment.

Effects on system behavior

Not applicable.

Interface changes

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[technolojin]

@wep21
Since I could not reproduce the symptom, I would like to request you to test this.

[YoshiRi]

LGTM but I cannot reproduce the error. So, wait for nishimatsu-san.

[wep21]

LGTM