Report error log after vllm bench serve (#31808)

Signed-off-by: Elvir Crncevic <elvircrn@gmail.com>

vllm/benchmarks/serve.py

@@ -412,6 +412,12 @@ def calculate_metrics(
     # Find the time range across all successful requests
     successful_outputs = [output for output in outputs if output.success]
     failed_outputs = [output for output in outputs if not output.success]
+
+    if len(failed_outputs) > 0:
+        print("Failed requests during benchmark run detected (capping to 10):")
+        for i, err in enumerate(failed_outputs[:10]):
+            print(f"Error {i}: {err.error}")
+
     if successful_outputs:
         min_start_time = min(output.start_time for output in successful_outputs)
         max_end_time = max(