Dataset Viewer issue for codeparrot/xlcost-text-to-code
### Link

https://huggingface.co/datasets/codeparrot/xlcost-text-to-code

### Description

Error
```
Server Error
Status code:   400
Exception:     TypeError
Message:       'NoneType' object is not iterable
```
Before I did a minor change in the dataset script (removing some comments), the viewer was working but not properely, it wasn't showing the dataset subsets. But the data can be loaded successfully.

Thanks!

### Owner

Yes