Fix example return_after_run (#1082)

* ignore error when setting global tracing subscriber

* ignore unfocus event on window closed previously

* update example to show how to disable LogPlugin

crates/bevy_log/src/lib.rs

@@ -74,13 +74,13 @@ impl Plugin for LogPlugin {
                 app.resources_mut().insert_thread_local(guard);
                 let subscriber = subscriber.with(chrome_layer);
                 bevy_utils::tracing::subscriber::set_global_default(subscriber)
-                    .expect("Could not set global default tracing subscriber.");
+                    .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins");
             }
 
             #[cfg(not(feature = "tracing-chrome"))]
             {
                 bevy_utils::tracing::subscriber::set_global_default(subscriber)
-                    .expect("Could not set global default tracing subscriber.");
+                    .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins");
             }
         }
 
@@ -91,14 +91,14 @@ impl Plugin for LogPlugin {
                 tracing_wasm::WASMLayerConfig::default(),
             ));
             bevy_utils::tracing::subscriber::set_global_default(subscriber)
-                .expect("Could not set global default tracing subscriber.");
+                .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins");
         }
 
         #[cfg(target_os = "android")]
         {
             let subscriber = subscriber.with(android_tracing::AndroidLayer::default());
             bevy_utils::tracing::subscriber::set_global_default(subscriber)
-                .expect("Could not set global default tracing subscriber.");
+                .expect("Could not set global default tracing subscriber. If you've already set up a tracing subscriber, please disable LogPlugin from Bevy's DefaultPlugins");
         }
     }
 }

crates/bevy_winit/src/lib.rs

@@ -336,11 +336,19 @@ pub fn winit_runner(mut app: App) {
                     let mut focused_events =
                         app.resources.get_mut::<Events<WindowFocused>>().unwrap();
                     let winit_windows = app.resources.get_mut::<WinitWindows>().unwrap();
-                    let window_id = winit_windows.get_window_id(winit_window_id).unwrap();
-                    focused_events.send(WindowFocused {
-                        id: window_id,
-                        focused,
-                    });
+                    match (winit_windows.get_window_id(winit_window_id), focused) {
+                        (Some(window_id), _) => focused_events.send(WindowFocused {
+                            id: window_id,
+                            focused,
+                        }),
+                        // unfocus event for an unknown window, ignore it
+                        (None, false) => (),
+                        // focus event on an unknown window, this is an error
+                        _ => panic!(
+                            "Focused(true) event on unknown window {:?}",
+                            winit_window_id
+                        ),
+                    }
                 }
                 _ => {}
             },

examples/app/return_after_run.rs

@@ -8,6 +8,7 @@ fn main() {
         })
         .add_resource(ClearColor(Color::rgb(0.2, 0.2, 0.8)))
         .add_plugins(DefaultPlugins)
+        .add_system(system1.system())
         .run();
     println!("Running another App.");
     App::build()
@@ -15,7 +16,18 @@ fn main() {
             return_from_run: true,
         })
         .add_resource(ClearColor(Color::rgb(0.2, 0.8, 0.2)))
-        .add_plugins(DefaultPlugins)
+        .add_plugins_with(DefaultPlugins, |group| {
+            group.disable::<bevy::log::LogPlugin>()
+        })
+        .add_system(system2.system())
         .run();
     println!("Done.");
 }
+
+fn system1() {
+    info!("logging from first app");
+}
+
+fn system2() {
+    info!("logging from second app");
+}