[App] Improve debug triggering

src/lightning_app/CHANGELOG.md

@@ -56,11 +56,15 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 - Fixed the `enable_spawn` method of the `WorkRunExecutor` ([#15812](https://github.com/Lightning-AI/lightning/pull/15812)
 
+
 - Fixed Sigterm Handler causing thread lock which caused KeyboardInterrupt to hang ([#15881](https://github.com/Lightning-AI/lightning/pull/15881))
 
 - Fixed a bug where using `L.app.structures` would cause multiple apps to be opened and fail with an error in the cloud ([#15911](https://github.com/Lightning-AI/lightning/pull/15911))
 
 
+- Fixed detection of a Lightning App running in debug mode ([#15951](https://github.com/Lightning-AI/lightning/pull/15951))
+
+
 ## [1.8.3] - 2022-11-22
 
 ### Changed

src/lightning_app/utilities/app_helpers.py

@@ -511,14 +511,9 @@ def is_static_method(klass_or_instance, attr) -> bool:
     return isinstance(inspect.getattr_static(klass_or_instance, attr), staticmethod)
 
 
-def _debugger_is_active() -> bool:
-    """Return if the debugger is currently active."""
-    return hasattr(sys, "gettrace") and sys.gettrace() is not None
-
-
 def _should_dispatch_app() -> bool:
     return (
-        _debugger_is_active()
+        __debug__
         and not bool(int(os.getenv("LIGHTNING_DISPATCHED", "0")))
         and "LIGHTNING_APP_STATE_URL" not in os.environ
     )