FlexRIC v2.0.0 crashes when receiving a RIC_SUBSCRIPTION_RESPONSE with an unknown ric_id that has no corresponding pending event

FlexRIC v2.0.0 crashes when receiving a RIC_SUBSCRIPTION_RESPONSE with an unknown ric_id that has no corresponding pending event. The near-RT RIC uses assert() to enforce the existence of a pending event during response processing. A remote unauthenticated attacker can send a forged RIC_SUBSCRIPTION_RESPONSE to the near-RT RIC (port 36421) to cause SIGABRT in Debug builds or NULL pointer dereference (SIGSEGV) in Release builds.