[Model Runner V2] Fix openai.InternalServerError: Error code: 500 - 'list index out of range' (#45467)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

vllm/v1/worker/gpu/sample/states.py

@@ -56,6 +56,8 @@ class SamplingStates:
         num_logprobs = sampling_params.logprobs
         if num_logprobs is None:
             num_logprobs = NO_LOGPROBS
+        elif num_logprobs == -1:
+            num_logprobs = self.vocab_size
         self.num_logprobs[req_idx] = num_logprobs
 
     def apply_staged_writes(self) -> None: