[Core] Raise when non-multi-instance DP clients target a DP rank (#19227)

Signed-off-by: Jon Swenson <jmswen@gmail.com>

vllm/v1/engine/processor.py

@@ -226,6 +226,12 @@ class Processor:
         if prompt_adapter_request is not None:
             raise ValueError("V1 does not support prompt_adapter_request.")
 
+        data_parallel_size = self.vllm_config.parallel_config.data_parallel_size
+        if data_parallel_rank is not None and not (0 <= data_parallel_rank <
+                                                   data_parallel_size):
+            raise ValueError(f"data_parallel_rank {data_parallel_rank} "
+                             f"is out of range [0, {data_parallel_size}).")
+
         if arrival_time is None:
             arrival_time = time.time()