[UX] Log worker exit code when process dies unexpectedly (vllm-project#38641)

Signed-off-by: Nick Cao <ncao@redhat.com>
Co-authored-by: Claude <noreply@anthropic.com>

Author: NickCao

vllm/v1/executor/multiproc_executor.py

@@ -280,9 +280,12 @@ def monitor_workers():
                 logger.debug("MultiprocWorkerMonitor: shutdown already initiated")
                 return
             _self.is_failed = True
-            proc_name = next(h.proc.name for h in workers if h.proc.sentinel == died[0])
+            proc = next(h.proc for h in workers if h.proc.sentinel == died[0])
             logger.error(
-                "Worker proc %s died unexpectedly, shutting down executor.", proc_name
+                "Worker proc %s died unexpectedly (exit code: %s), "
+                "shutting down executor.",
+                proc.name,
+                proc.exitcode,
             )
             _self.shutdown()
             callback = _self.failure_callback