[Bug]: GraphRAG doesn't get generated - 400 Please use a valid role: user, model.

[marcfon]

Is there an existing issue for the same bug?

• [X] I have checked the existing issues.

Branch name

main

Commit ID

--

Other environment information

* dev version

KB settings
* chunk method: knowledge graph
* embedding model: Gemini (tried others as well)

Actual behavior

Traceback (most recent call last):
  File "/ragflow/graphrag/graph_extractor.py", line 128, in __call__
    result, token_count = self._process_document(text, prompt_variables)
  File "/ragflow/graphrag/graph_extractor.py", line 177, in _process_document
    if response.find("**ERROR**") >=0: raise Exception(response)
Exception: **ERROR**: 400 Please use a valid role: user, model.
**ERROR**: contents must not be empty```

### Expected behavior

_No response_

### Steps to reproduce

```Markdown
Add a plain text document to the KB and parse.

Additional information

No response