In both `process_dataset_mc` and `process_dataset_data` of [hillas_preprocessing.py](hillas_preprocessing.py), the following line throws an error: ```python camera = event.inst.subarray.tel[tel_id].camera ``` Indeed, `subarray` in ctapipe is not anymore a property of each event, but of the particular event source (see https://github.com/cta-observatory/ctapipe/pull/1157).