lib.App: Restore caller's event loop in run()

run() remembers the thread's current event loop before creating a new
one only when the app does not own a loop yet. The finally block,
however, always restores the remembered loop or unsets the loop when
there was none. So when a caller passes its own event loop to the App
constructor and has set it as the thread's current loop, run() unsets
the thread's loop on the way out, although it never changed it.

Remember the thread's current event loop unconditionally and restore
it in the finally block; for a caller-provided loop that is a no-op.

Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v0.84.2
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/App.py

@@ -513,9 +513,8 @@ class App:  # export
         return self.__parser
 
     def run(self, argv: list[str] | None = None) -> None:
-        previous_eloop: asyncio.AbstractEventLoop | None = None
+        previous_eloop = _get_current_event_loop()
         if self.__eloop is None:
-            previous_eloop = _get_current_event_loop()
             eloop = asyncio.new_event_loop()
             asyncio.set_event_loop(eloop)
             self.__eloop = eloop