OpcUaServer crashes if i stop the server while UaExpert is connected and monitoring Tags

I have implemented a opcuaserver using opcua c++ sdk . The Server crashes in following scenario

1.OpcuaServer is connected to UaExpert(OpcuaClient)

2. UaExpert is monitoring tags. Tags are Monitered while server is connected

3.At this point if the server is stopped , It crashes

Exception Callstack