[App] Resolve a condition bug with spawning (#15812)

Co-authored-by: Carlos Mocholí <carlossmocholi@gmail.com>

src/lightning_app/CHANGELOG.md

@@ -43,6 +43,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed the PyTorch Inference locally on GPU ([#15813](https://github.com/Lightning-AI/lightning/pull/15813))
 
 
+- Fixed the `enable_spawn` method of the `WorkRunExecutor` ([#15812](https://github.com/Lightning-AI/lightning/pull/15812))
+
+
 ## [1.8.2] - 2022-11-17
 
 ### Added

src/lightning_app/utilities/proxies.py

@@ -17,6 +17,7 @@
 from deepdiff import DeepDiff, Delta
 from lightning_utilities.core.apply_func import apply_to_collection
 
+from lightning_app.core.queues import MultiProcessQueue
 from lightning_app.storage import Path
 from lightning_app.storage.copier import _Copier, _copy_files
 from lightning_app.storage.drive import _maybe_create_drive, Drive
@@ -357,7 +358,7 @@ def enable_spawn(self) -> Generator:
         yield
 
     def _clean_queues(self):
-        if "LIGHTNING_APP_STATE_URL" in os.environ:
+        if not isinstance(self.work._request_queue, MultiProcessQueue):
             self.work._request_queue = self.work._request_queue.to_dict()
             self.work._response_queue = self.work._response_queue.to_dict()