Fix bsn nested entity references (bevyengine#24742)

fix nested named entities

# Objective

Fix nested entity references

## Solution

Iterate over entity references instead of only insert first

## Testing

Added relevent test case

---------

Co-authored-by: Heart <>

Author: HeartofPhos

crates/bevy_scene/src/lib.rs

@@ -2959,4 +2959,65 @@ mod tests {
             .unwrap();
         assert!(entity.get::<Foo>().is_some());
     }
+
+    #[test]
+    fn scene_nested_entity_references() {
+        let mut app = test_app();
+        let world = app.world_mut();
+
+        #[derive(Component, FromTemplate)]
+        struct Ref(Entity);
+
+        let patch = bsn! {
+            #patch
+            Children [
+                Ref(#patch)
+            ]
+        };
+
+        let root = bsn! {
+            #root
+            patch
+        };
+
+        let expected_id = Some(world.spawn_scene(root).unwrap().id());
+        let actual_id = world
+            .query::<&Ref>()
+            .query(world)
+            .single()
+            .ok()
+            .map(|r| r.0);
+
+        assert_eq!(expected_id, actual_id);
+    }
+
+    #[test]
+    fn scene_list_nested_entity_references() {
+        let mut app = test_app();
+        let world = app.world_mut();
+
+        #[derive(Component, FromTemplate)]
+        struct Ref(Entity);
+
+        let patch = bsn! {
+            #patch
+            Children [
+                Ref(#patch)
+            ]
+        };
+
+        let root = bsn_list! {
+            #root patch
+        };
+
+        let expected_id = Some(world.spawn_scene_list(root).unwrap()[0]);
+        let actual_id = world
+            .query::<&Ref>()
+            .query(world)
+            .single()
+            .ok()
+            .map(|r| r.0);
+
+        assert_eq!(expected_id, actual_id);
+    }
 }

crates/bevy_scene/src/resolved_scene.rs

@@ -226,7 +226,7 @@ impl ResolvedScene {
         writer_ops: impl FnOnce(&mut TemplateContext, &mut BundleWriter),
     ) -> Result<(), ApplySceneError> {
         let mut bundle_writer = bundle_scratch.writer();
-        if let Some(entity_reference) = self.entity_references.first().copied() {
+        for entity_reference in self.entity_references.iter().copied() {
             context
                 .entity_references
                 .set(entity_reference, context.entity.id());