An empty README.yaml is not handled correctly.
If a README.yaml file is empty we get this error:
File "/opt/eresearch/ddc/bin/ddc.py", line 440, in main
(data, warnings) = sanitise_data(data, deny_list)
File "/opt/eresearch/ddc/bin/ddc.py", line 202, in sanitise_data
for key in doc_copy.keys():
AttributeError: 'NoneType' object has no attribute 'keys'