fixes #79, reduce crash possibility, not sure whether still got it yet

Author: yjpark

crates/notation_bevy/src/app/app.rs

@@ -134,10 +134,20 @@ fn setup_camera(mut commands: Commands) {
 
 fn load_tab(
     mut state: ResMut<NotationAppState>,
+    entities: Query<Entity, With<GlobalTransform>>,
     assets: ResMut<Assets<TabAsset>>,
     mut evts: EventWriter<AddTabEvent>,
 ) {
     if state.window_width > 0.0 && state.window_height > 0.0 && state.tab.is_none() && state.parse_error.is_none() {
+        let mut count = 0;
+        for _ in entities.iter() {
+            count += 1;
+        }
+        //A bit hacky to make sure despawning finished, otherwise might got panic with "Entity not exist"
+        if count > 1 {
+            println!("Waiting for entities to be despawned: {}", count);
+            return;
+        }
         if let Some(asset) = assets.get(&state.tab_asset) {
             match Tab::try_parse_arc(asset.tab.clone()) {
                 Ok(tab) => {

crates/notation_bevy/src/guitar/guitar_string.rs

@@ -148,11 +148,15 @@ impl ShapeOp<NotationTheme, OutlineRectangle> for GuitarStringData {
             shapes::RectangleOrigin::TopLeft
         };
         let color = if self.upper {
-            theme
-                .colors
-                .strings
-                .string
-                .of_state(&PlayingState::Idle)
+            if self.is_muted() {
+                theme.colors.strings.muted
+            } else {
+                theme
+                    .colors
+                    .strings
+                    .string
+                    .of_state(&PlayingState::Idle)
+            }
         } else if self.is_muted() {
             theme.colors.strings.muted
         } else if self.state.is_current() && self.note.is_some() {

crates/notation_bevy/src/viewer/control.rs

@@ -91,6 +91,9 @@ impl ControlView {
         state: &mut NotationAppState,
         viewer_query: &Query<(Entity, &Arc<NotationViewer>), With<Arc<NotationViewer>>>,
     ) {
+        if state.tab.is_none() {
+            return;
+        }
         for (entity, viewer) in viewer_query.iter() {
             if viewer.uuid == state.viewer_uuid {
                 commands.entity(entity).despawn_recursive();