Error has occured, when I start training schenet model. ValueError: Expected a parent

Hi everyone!, I tried to proceed with the study with my own data using Schnetpack’s tutorial on google colab, but an error occurred! Does anyone know why this message is occured ?
Please let me know how I can fix it. Thank you.
Error message is below.

ValueError                                Traceback (most recent call last)
<ipython-input-21-036afe972bfc> in <module>
----> 1, datamodule=new_dataset)

6 frames
/usr/local/lib/python3.8/dist-packages/pytorch_lightning/utilities/ in is_overridden(method_name, instance, parent)
     32             parent = pl.Callback
     33         if parent is None:
---> 34             raise ValueError("Expected a parent")
     35     from lightning_utilities.core.overrides import is_overridden

ValueError: Expected a parent

Source code (google colabo) is here.

schnetpack tutorial