Fix segfault after loading posegraph

[samiamlabs]

Basic Info

I was getting a segfault in in localization_slam_toolbox_node after loading a posegraph from a file here in the code: https://github.com/SteveMacenski/slam_toolbox/blob/ae68b851094668738fd32e8dc6e72e18fd15a965/src/loop_closure_assistant.cpp#L189

The problem is that the LoopClosureAssistant was created with a raw pointer to a karto::Mapper instance from a unique pointer. The raw pointer is not replaced when a new serialized pose graph is loaded. Trying to call functions on the mapper_ pointer in the LoopClosureAssistant after that will cause a segfault.

| Primary OS tested on | Ubuntu | | Robotic platform tested on | gazebo simulation of Husky |

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Description of contribution in a few bullet points

• Added a setter for the mapper_ pointer to LoopClosureAssistant
• Updated the mapper used by LoopClosureAssistant in loadSerializedPoseGraph

Future work that may be required

It seems a bit strange to me that LoopClosureAssistant is using raw pointers rather that smart pointers. I suspect there is a reason for this thought... If not, it not we should probably change it so it uses smart pointers and avoid segfaults like this.

[SteveMacenski]

It seems a bit strange to me that LoopClosureAssistant is using raw pointers rather that smart pointers. I suspect there is a reason for this thought...

At the time of writing, I had just gotten out of several months working in the core of lib KartoSDK which has raw pointers galore for the graph-SLAM representations so it was just the headspace I was in. Plus,