Closes#35727
---
Several internal code paths raised a bare `ValueError` with no message,
so when one of these conditions tripped, users saw a traceback with no
explanation of what actually went wrong.
This adds descriptive messages to each of those `raise ValueError`
calls:
- `FewShotPromptWithTemplates._get_examples` / `_aget_examples` — when
neither `examples` nor `example_selector` is set.
- Prompt `loading` — when a referenced template file uses an unsupported
(non-`.txt`) format.
- The LangSmith document loader — when both `client` and `client_kwargs`
are supplied.
- The Anthropic file-search middleware brace expansion — for unbalanced
or empty brace patterns.
Made by [Open SWE](https://openswe.vercel.app)
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Co-authored-by: open-swe[bot] <open-swe@users.noreply.github.com>
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