I'm using my dataset with your codes, but this line:
graph, linetracks = _mrg.merging(linker, all_2d_segs, imagecols, seg3d_list, neighbors, var2d=cfg["merging"]["var2d"])
gives that error:
terminate called after throwing an instance of 'std::out_of_range' what(): map::at Aborted (core dumped)