Repository: confident-ai/deepeval
Issue: IndexError list index out of range in `Synthesizer.generate_goldens_from_docs()`
Root cause: Validation Gap

**Describe the bug**
After I update the code to the latest version v3.0.8, the following code will throw "IndexError: list index out of range".
```python

from deepeval.synthesizer import Synthesizer
from deepeval.synthesizer.config import ContextConstructionConfig
import os
from dotenv import load_dotenv

load_dotenv()


synthesizer = Synthesizer()
synthesizer.generate_goldens_from_docs(
    document_paths=["example.txt"],
    context_construction_config=ContextConstructionConfig(
        max_contexts_per_document=1, chunk_size=2048
    ),
)
``` 
**Expected behavior**
The code should work without errors.


GTG

@ObsisMc can you show the full error stack? 

I found that only when `max_contexts_per_document=1`, will the error occur, and if it is larger than 1, the code can work.

The error is:
```shell

Traceback (most recent call last):
  File "/home/zrh/Repository/gitrepo/deepeval/test.py", line 10, in <module>
    synthesizer.generate_goldens_from_docs(
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 145, in generate_goldens_from_docs
    goldens = loop.run_until_complete(
              ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/zrh/Software/Environment/anaconda/envs/llama/lib/python3.11/asyncio/base_events.py", line 654, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 300, in a_generate_goldens_from_docs
    goldens = await self.a_generate_goldens_from_contexts(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 564, in a_generate_goldens_from_contexts
    await asyncio.gather(*tasks)
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 1323, in task_wrapper
    return await func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 715, in _a_generate_from_context
    results = await asyncio.gather(*tasks)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 1323, in task_wrapper
    return await func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/zrh/Repository/gitrepo/deepeval/deepeval/synthesizer/synthesizer.py", line 695, in process_input
    source_files[index] if source_files is not None else None
    ~~~~~~~~~~~~^^^^^^^
IndexError: list index out of range

```

In addition, here is the [example.txt](https://github.com/user-attachments/files/20716960/example.txt) I tested.

By the way, during the data generation, the LLM may occasionally generate wrong format at some step , which will crash the entire program. Do you have a plan to implement kind of mechanism to retry/skip these cases?

Tm_[]()gm![IMG_20250611_020633_710.jpg](https://github.com/user-attachments/assets/0acf0392-b131-4f4a-84e4-472ac688af91)

_

hey @ObsisMc not at the moment, but we'll see how we can include it some way