Options inside Config structs don't default to getting wrapped by another option. That means the parser can't tell if the struct was initialized to None or was missing. So specify that we want to wrap log_file with another option so it can be properly differentiated.
Options inside Config structs don't default to getting wrapped by another option. That means the parser can't tell if the struct was initialized to None or was missing. So specify that we want to wrap log_file with another option so it can be properly differentiated.