Question Attempted to access ComponentLookup which has been invalidated by a structural change.

Hello the following error is thrown

Code (CSharp):

1. ObjectDisposedException: Attempted to access ComponentLookup<Unity.Collections.NativeText.ReadOnly> which has been invalidated by a structural change.

for the following code:

Code (CSharp):

1. using Unity.Burst;
2. using Unity.Collections;
3. using Unity.Entities;
4. using Unity.Mathematics;
5. using Unity.Rendering;
6. using Unity.Transforms;
7. using UnityEngine;
8. using Random = Unity.Mathematics.Random;
9.  
10. [BurstCompile]
11. partial struct MonsterSpawningSystem : ISystem
12. {
13.     [ReadOnly] ComponentLookup<WorldTransform> WorldTransformLookup;
14.     public Entity player;
15.     public float timeUntilNextMonster;
16.     public EntityQuery monsterSpawnerQuery;
17.     public Random random;
18.  
19.     [BurstCompile]
20.     public void OnCreate(ref SystemState state)
21.     {
22.         WorldTransformLookup = state.GetComponentLookup<WorldTransform>(true);
23.         monsterSpawnerQuery = SystemAPI.QueryBuilder().WithAll<MonsterSpawner>().WithAspect<TimerAspect>().Build();
24.         random = new Random(8328732);
25.     }
26.  
27.     [BurstCompile]
28.     public void OnDestroy(ref SystemState state)
29.     {
30.      
31.     }
32.  
33.     //[BurstCompile]
34.     public void OnUpdate(ref SystemState state)
35.     {
36.         var dt = SystemAPI.Time.DeltaTime;
37.         //var config = SystemAPI.GetSingleton<Config>();
38.  
39.         var ecbSingleton = SystemAPI.GetSingleton<BeginSimulationEntityCommandBufferSystem.Singleton>();
40.         var ecb = ecbSingleton.CreateCommandBuffer(state.WorldUnmanaged);
41.         foreach (var (monsterSpawner, timerAspect) in SystemAPI.Query<MonsterSpawner, TimerAspect>())
42.         {
43.             if (timerAspect.isNextNow(ref random, dt))
44.             {
45.                 Debug.Log(monsterSpawner.SpawnCenter);
46.                 var instance = ecb.Instantiate(monsterSpawner.MonsterPrefab);
47.                 var positionNoise = new float3(random.NextFloat(), 0, random.NextFloat()) * 5;
48.                 var spawnAt = WorldTransformLookup[monsterSpawner.SpawnCenter];
49.                 var spawnAtPosition = positionNoise;
50.                 //Debug.Log(spawnAtPosition);
51.                 var transform = LocalTransform.FromPosition(spawnAtPosition);
52.                 Debug.Log(transform);
53.                 ecb.SetComponent(instance, transform);
54.             }
55.         }
56.     }
57. }

Any pointers on how to debug this would help me a lot!
Thanks

 

Thanks to the very helpful discord (@tertle ), I could resolve this and what one needs to do is call

Code (CSharp):

1. WorldTransformLookup.Update(ref state);

every frame