Avoid race condition with UDP voice server starting in ESPHome (#111644)

* Avoid race condition with UDP server starting

* Fix test

homeassistant/components/esphome/voice_assistant.py

@@ -160,10 +160,10 @@ class VoiceAssistantUDPServer(asyncio.DatagramProtocol):
 
     async def _iterate_packets(self) -> AsyncIterable[bytes]:
         """Iterate over incoming packets."""
-        if not self.is_running:
-            raise RuntimeError("Not running")
-
         while data := await self.queue.get():
+            if not self.is_running:
+                break
+
             yield data
 
     def _event_callback(self, event: PipelineEvent) -> None:

tests/components/esphome/test_voice_assistant.py

@@ -224,9 +224,13 @@ async def test_udp_server_queue(
 
     voice_assistant_udp_server_v1.close()
 
-    with pytest.raises(RuntimeError):
-        async for data in voice_assistant_udp_server_v1._iterate_packets():
-            assert data == bytes(1024)
+    # Stopping the UDP server should cause _iterate_packets to break out
+    # immediately without yielding any data.
+    has_data = False
+    async for _data in voice_assistant_udp_server_v1._iterate_packets():
+        has_data = True
+
+    assert not has_data, "Server was stopped"
 
 
 async def test_error_calls_handle_finished(