move extract after scope to make input processing closer to main app run

Author: hymm

crates/bevy_app/src/app.rs

@@ -159,15 +159,15 @@ impl App {
             .map(|e| e.0.clone());
         ComputeTaskPool::init(TaskPool::default).scope(thread_executor, |scope| {
             if self.run_once {
-                for sub_app in self.sub_apps.values_mut() {
-                    (sub_app.extract)(&mut self.world, &mut sub_app.app);
-                }
                 for sub_app in self.sub_apps.values_mut() {
                     scope.spawn(async { (sub_app.runner)(&mut sub_app.app) });
                 }
             }
             self.schedule.run(&mut self.world);
         });
+        for sub_app in self.sub_apps.values_mut() {
+            (sub_app.extract)(&mut self.world, &mut sub_app.app);
+        }
         self.run_once = true;
     }