[Bugfix] Fix edge-case crash when using chat with the Mistral Tekken Tokenizer

[tjohnson31415]

When running the server with:

vllm serve mistralai/Ministral-8B-Instruct-2410 --tokenizer-mode=mistral

it is possible to crash the engine/server with a simple request:

curl http://localhost:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
      "model": "mistralai/Ministral-8B-Instruct-2410",
      "messages": [
        {
          "role": "user",
          "content": "寫一首關於勇敢的水手的詩"
        }
      ]
  }'

The stack trace includes:

ERROR 11-05 20:58:45 engine.py:147]   File "/workspace/my-vllm/lib64/python3.12/site-packages/vllm/engine/output_processor/single_step.py", line 122, in _process_sequence_group_outputs
ERROR 11-05 20:58:45 engine.py:147]     new_char_count = self.detokenizer.decode_sequence_inplace(
ERROR 11-05 20:58:45 engine.py:147]                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 11-05 20:58:45 engine.py:147]   File "/workspace/my-vllm/lib64/python3.12/site-packages/vllm/transformers_utils/detokenizer.py", line 117, in decode_sequence_inplace
ERROR 11-05 20:58:45 engine.py:147]     seq.read_offset) = convert_prompt_ids_to_tokens(
ERROR 11-05 20:58:45 engine.py:147]                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 11-05 20:58:45 engine.py:147]   File "/workspace/my-vllm/lib64/python3.12/site-packages/vllm/transformers_utils/detokenizer_utils.py", line 64, in convert_prompt_ids_to_tokens
ERROR 11-05 20:58:45 engine.py:147]     new_tokens = tokenizer.convert_ids_to_tokens(
ERROR 11-05 20:58:45 engine.py:147]                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 11-05 20:58:45 engine.py:147]   File "/workspace/my-vllm/lib64/python3.12/site-packages/vllm/transformers_utils/tokenizers/mistral.py", line 288, in convert_ids_to_tokens
ERROR 11-05 20:58:45 engine.py:147]     tokens = [self.tokenizer.id_to_byte_piece(id) for id in ids]
ERROR 11-05 20:58:45 engine.py:147]               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 11-05 20:58:45 engine.py:147]   File "/workspace/my-vllm/lib64/python3.12/site-packages/mistral_common/tokens/tokenizers/tekken.py", line 280, in id_to_byte_piece
ERROR 11-05 20:58:45 engine.py:147]     return self._model.decode_single_token_bytes(token_id - self.num_special_tokens)
ERROR 11-05 20:58:45 engine.py:147]            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 11-05 20:58:45 engine.py:147]   File "/workspace/my-vllm/lib64/python3.12/site-packages/tiktoken/core.py", line 272, in decode_single_token_bytes
ERROR 11-05 20:58:45 engine.py:147]     return self._core_bpe.decode_single_token_bytes(token)
ERROR 11-05 20:58:45 engine.py:147]            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ERROR 11-05 20:58:45 engine.py:147] OverflowError: out of range integral type conversion attempted

I traced the cuase to being the id for a special token passed in to id_to_byte_piece. The chat template ends with the [/INST] special token and generating a token for a symbolic language like chinese is likely to send the code down the path where it must convert token ids to bytes for the first generated token. The end of the prompt is included in the "prefix" part of the incremental detokenization, thus triggering the error.

The solution proposed in this PR is to explicitly remove special token ids from the list of tokens passed in to convert_ids_to_tokens (it requires skip_special_tokens=True anyways).

---

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[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. @tjohnson31415 please rebase it. https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[DarkLight1337]

Thanks for the fix!