Drop the event callback before exiting on macOS (#1954)

* Drop the event callback before exiting

* Update the changelog

* Apply suggestion from review

Co-authored-by: Markus Røyset <maroider@protonmail.com>

* Apply review suggestions

Co-authored-by: Markus Røyset <maroider@protonmail.com>

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- On macOS, drop the event callback before exiting.
 - On Android, implement `Window::request_redraw`
 - **Breaking:** On Web, remove the `stdweb` backend.
 - Added `Window::focus_window`to bring the window to the front and set input focus.

src/platform_impl/macos/event_loop.rs

@@ -174,10 +174,12 @@ impl<T> EventLoop<T> {
             let () = msg_send![app, run];
 
             if let Some(panic) = self.panic_info.take() {
+                drop(self._callback.take());
                 resume_unwind(panic);
             }
             AppState::exit();
         });
+        drop(self._callback.take());
     }
 
     pub fn create_proxy(&self) -> Proxy<T> {