[Misc] Use VLLMValidationError consistently in SamplingParams._verify_args

[umut-polat]

some parameter checks in _verify_args raised plain ValueError or TypeError while others already used VLLMValidationError. the custom exception carries parameter and value which the api layer uses to build structured error responses for clients.

migrated all remaining ValueError/TypeError raises in _verify_args to VLLMValidationError with appropriate parameter and value kwargs:

• n (type check + range)
• presence_penalty
• frequency_penalty
• repetition_penalty
• top_k (range + type check)
• min_p
• min_tokens (range + max_tokens comparison)
• stop_token_ids
• stop (empty string + detokenize)

no changes to error message text or validation logic.

[gemini-code-assist]

Code Review

This pull request correctly refactors the validation logic in SamplingParams._verify_args to consistently use VLLMValidationError. This change improves structured error reporting for API clients. The implementation is accurate and aligns with the pull request's goal. For future work, you might consider extending this refactoring to other validation methods within the SamplingParams class (e.g., _verify_greedy_sampling, _validate_spec_decode) to achieve full consistency.

[mergify]

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[mergify]

Hi @umut-polat, the pre-commit checks have failed. Please run:

uv pip install pre-commit
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

Tip

Is mypy failing?

mypy is run differently in CI. If the failure is related to this check, please use the following command to run it locally:

# For mypy (substitute "3.10" with the failing version if needed)
pre-commit run --hook-stage manual mypy-3.10