Check for valid tracker pointer.
Check for valid tracker pointer.

CppMicroServices/CppMicroServices,ksubramz/CppMicroServices,ksubramz/CppMicroServices,CppMicroServices/CppMicroServices,CppMicroServices/CppMicroServices,saschazelzer/CppMicroServices,ksubramz/CppMicroServices,ksubramz/CppMicroServices,CppMicroServices/CppMicroServices,ksubramz/CppMicroServices,saschazelzer/CppMicroServices,CppMicroServices/CppMicroServices