@2454302 Make ip_route_mgr's getter panic-free.
@2454302 Make ip_route_mgr's getter panic-free.

aristanetworks/EosSdk,tsuna/EosSdk,tsuna/EosSdk,tsuna/EosSdk,aristanetworks/EosSdk,aristanetworks/EosSdk,tsuna/EosSdk,aristanetworks/EosSdk