Avoid failed CHECK when running offline node with no bags. (#777)
Avoid failed CHECK when running offline node with no bags. (#777)

Bug introduced in #680.
googlecartographer/cartographer_ros,wohe/cartographer_ros,cartographer-project/cartographer_ros,cartographer-project/cartographer_ros,googlecartographer/cartographer_ros,wohe/cartographer_ros,damonkohler/cartographer_ros,wohe/cartographer_ros,damonkohler/cartographer_ros,cartographer-project/cartographer_ros,damonkohler/cartographer_ros,googlecartographer/cartographer_ros