ValueError: max() arg is an empty sequence

Just upgraded from 0.6.2 to 0.71 and my script doesn't run anymore. I get the error:

`ValueError: max() arg is an empty sequence`

This is the function causing the issue:

```
def classify_content_by_speaker(content):
doc = nlp(content)
category = max(doc.cats, key=doc.cats.get)
speaker = speaker_mapping.get(category, "Unknown Speaker")
reason = f"Assigned to {speaker} based on LLM classification for category {category}."
return {'speaker': speaker, 'reason': reason}
```

Downgrading back to 0.6.2 fixes the issue.

Start by reproducing the provided classify_content_by_speaker function with spaCy-LLM 0.71, then compare its behavior with version 0.6.2, focusing on why doc.cats is empty. Trace the classification result and identify the expected behavior for this upgrade; done means the regression is explained and a verified fix or compatibility guidance is available.

Written by the indexing model from the issue text.