Bounds check async concurrency value

Author: sjmonson

src/guidellm/scheduler/worker.py

@@ -224,7 +224,15 @@ def process_loop_asynchronous(
         process_id: int,
     ):
         async def _process_runner():
-            pending = asyncio.Semaphore(max_concurrency) if max_concurrency else None
+            if max_concurrency is not None:
+                if max_concurrency < 1:
+                    raise ValueError(
+                        f"max_concurrency must be greater than 0, got {max_concurrency}"
+                    )
+
+                pending = asyncio.Semaphore(max_concurrency)
+            else:
+                pending = None
 
             while (
                 process_request := await self.get_request(requests_queue)