Bug - Dataset summary generation failing due to log file set to None

[shubham-skr]

The dataset summary generation was failing when log_file is None, as at line 76 it does not check if the log_file is None resulting in an exception.

I fixed the problem by adding the code to check if log_file is None before write operation.

[XenonMolecule]

Thanks for catching this! Looks good to me, will merge if the checks all pass