Added a fix in create_or_get_logger function to check logger_ptr prior to use (#748)

[Syed-Shahrukh-OSSRevival]

Added check to ensure logger_ptr is not null. logger_ptr is set to _find_logger and there is a possibility for this function to return nullptr.

return (search_it != std::end(_loggers) && search_it->get()->get_logger_name() == target)
      ? search_it->get()
      : nullptr;

[odygrd]

Thanks for the PR!