From a272c9f8eb56db8ffe622a32671bc521892bc9a9 Mon Sep 17 00:00:00 2001
From: robtfm <50659922+robtfm@users.noreply.github.com>
Date: Sat, 29 Apr 2023 14:21:09 +0100
Subject: [PATCH 1/3] check parent

---
 crates/bevy_scene/src/scene_spawner.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/crates/bevy_scene/src/scene_spawner.rs b/crates/bevy_scene/src/scene_spawner.rs
index 5a46aa14e256c..e84fe11516025 100644
--- a/crates/bevy_scene/src/scene_spawner.rs
+++ b/crates/bevy_scene/src/scene_spawner.rs
@@ -267,6 +267,12 @@ impl SceneSpawner {
         let scenes_with_parent = std::mem::take(&mut self.scenes_with_parent);
 
         for (instance_id, parent) in scenes_with_parent {
+            if world.get_entity(parent).is_none() {
+                // parent has been deleted, despawn the instance
+                self.instances_to_despawn.push(instance_id);
+                continue;
+            }
+
             if let Some(instance) = self.spawned_instances.get(&instance_id) {
                 for entity in instance.entity_map.values() {
                     // Add the `Parent` component to the scene root, and update the `Children` component of

From 23bfdc91c44ffb06235277ff73959d3bddf3e2c7 Mon Sep 17 00:00:00 2001
From: robtfm <50659922+robtfm@users.noreply.github.com>
Date: Sat, 29 Apr 2023 23:06:45 +0100
Subject: [PATCH 2/3] despawn before loading

---
 crates/bevy_scene/src/scene_spawner.rs | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/crates/bevy_scene/src/scene_spawner.rs b/crates/bevy_scene/src/scene_spawner.rs
index e84fe11516025..0381bae7466b5 100644
--- a/crates/bevy_scene/src/scene_spawner.rs
+++ b/crates/bevy_scene/src/scene_spawner.rs
@@ -267,12 +267,6 @@ impl SceneSpawner {
         let scenes_with_parent = std::mem::take(&mut self.scenes_with_parent);
 
         for (instance_id, parent) in scenes_with_parent {
-            if world.get_entity(parent).is_none() {
-                // parent has been deleted, despawn the instance
-                self.instances_to_despawn.push(instance_id);
-                continue;
-            }
-
             if let Some(instance) = self.spawned_instances.get(&instance_id) {
                 for entity in instance.entity_map.values() {
                     // Add the `Parent` component to the scene root, and update the `Children` component of
@@ -322,6 +316,26 @@ impl SceneSpawner {
 
 pub fn scene_spawner_system(world: &mut World) {
     world.resource_scope(|world, mut scene_spawner: Mut<SceneSpawner>| {
+        // remove any loading instances where parent is deleted
+        let mut dead_instances = HashSet::default();
+        scene_spawner
+            .scenes_with_parent
+            .retain(|(instance, parent)| {
+                let retain = world.get_entity(*parent).is_some();
+
+                if !retain {
+                    dead_instances.insert(*instance);
+                }
+
+                retain
+            });
+        scene_spawner
+            .dynamic_scenes_to_spawn
+            .retain(|(_, instance)| !dead_instances.contains(instance));
+        scene_spawner
+            .scenes_to_spawn
+            .retain(|(_, instance)| !dead_instances.contains(instance));
+
         let scene_asset_events = world.resource::<Events<AssetEvent<DynamicScene>>>();
 
         let mut updated_spawned_scenes = Vec::new();

From 2c87dc9a6affc4f91b801f79bd31441c53404f80 Mon Sep 17 00:00:00 2001
From: robtfm <50659922+robtfm@users.noreply.github.com>
Date: Sun, 30 Apr 2023 01:27:31 +0100
Subject: [PATCH 3/3] missed an import somehow

---
 crates/bevy_scene/src/scene_spawner.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/bevy_scene/src/scene_spawner.rs b/crates/bevy_scene/src/scene_spawner.rs
index 0381bae7466b5..94abfccc39e15 100644
--- a/crates/bevy_scene/src/scene_spawner.rs
+++ b/crates/bevy_scene/src/scene_spawner.rs
@@ -8,7 +8,7 @@ use bevy_ecs::{
     world::{Mut, World},
 };
 use bevy_hierarchy::{AddChild, Parent};
-use bevy_utils::{tracing::error, HashMap};
+use bevy_utils::{tracing::error, HashMap, HashSet};
 use thiserror::Error;
 use uuid::Uuid;