Why my Job freeze the Unity silently

I tried to use the Jobs with Entities but looks like I am doing something horrible and The Unity just freeze on me. For example, you can easily forget to add Unity.Collections; and it will not complain. I would love if anyone can point me what is wrong. I suspect I can not handle Rotation like that, but I can't think why? Or why it is freezing. This is supposed to be another thread right? (Unity Vers. 2018.1.0b12 - from Welcome post, VS 2017 Community).

Code (CSharp):

1.  
2. using Unity.Jobs;
3. using UnityEngine;
4. using Unity.Entities;
5. using Unity.Transforms;
6. using Unity.Rendering;
7. using Unity.Collections;
8.  
9.  
10. // I know BootTime is working correct as I am using a ComponentSystem to play with entities' position. But after 1 frame Unity Freeze. I have only added below JobComponent System and Freezing start.
11.  
12. public sealed class BootTime
13. {
14.  
15.     public static EntityArchetype PlayerArchetype;
16.  
17.     public static MeshInstanceRenderer PlayerLook;
18.  
19.     [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.AfterSceneLoad)]
20.     public static void Init()
21.     {
22.         var entityManager = World.Active.GetOrCreateManager<EntityManager>();
23.  
24.         PlayerArchetype = entityManager.CreateArchetype(typeof(Position3D),typeof(TransformMatrix),typeof(Position),typeof(Rotation));
25.  
26.         PlayerLook = GetLookFromPrototype("PlayerRenderPrototype");
27.  
28.         for (int i = 0; i < 50; i++)
29.         {
30.             var player = entityManager.CreateEntity(PlayerArchetype);
31.  
32.             entityManager.AddSharedComponentData(player, PlayerLook);
33.  
34.         }
35.      
36.     }
37.  
38.  
39.  
40.     private static MeshInstanceRenderer GetLookFromPrototype(string protoName)
41.     {
42.         var proto = GameObject.Find(protoName);
43.         Debug.Log(proto.name + " this is the name found");
44.         var result = proto.GetComponent<MeshInstanceRendererComponent>().Value;
45.         Object.Destroy(proto);
46.         return result;
47.     }
48. }
49.  
50. // Looks like this should be the traitor, but why? Ofcourse it can be anything. I have no clue I am writing 64 to the last schedule forexample :D
51.  
52. public class SystemhereWithJob : JobComponentSystem
53. {
54.     [ComputeJobOptimization]
55.     public struct GoGrazy : IJobProcessComponentData<Rotation>
56.     {
57.  
58.  
59.         public void Execute(ref Rotation rotation)
60.         {
61.  
62.             rotation.Value = Random.rotation;
63.         }
64.     }
65.  
66.     protected override JobHandle OnUpdate(JobHandle inputDeps)
67.     {
68.         var job = new GoGrazy { };
69.         return job.Schedule(this, 64, inputDeps);
70.     }
71. }

Edit : Only after 4 mins I found it But I think Compiler should have shout on it !

Code (CSharp):

1. public void Execute(ref Rotation rotation)
2.         {
3.  
4.             rotation.Value = Random.rotation;
5.         }

Looks like this is unacceptable and it will crash Unity even though it will do it very silent.

The correct way of doing it is:

Code (CSharp):

1. public class SystemhereWithJob : JobComponentSystem
2. {
3.     [ComputeJobOptimization]
4.     public struct GoGrazy : IJobProcessComponentData<Rotation>
5.     {
6.         public Quaternion randomRot;
7.  
8.         public void Execute(ref Rotation rotation)
9.         {
10.  
11.             rotation.Value = randomRot;
12.         }
13.     }
14.  
15.     protected override JobHandle OnUpdate(JobHandle inputDeps)
16.     {
17.         var job = new GoGrazy { randomRot = Random.rotation };
18.         return job.Schedule(this, 64, inputDeps);
19.     }
20. }

Notice how I created a randomRot Quaternion, and it is supplied to job at Schedule part.

I mean it makes sense. On another thread you should not call Random.value from main Unity thread but maybe a warning would be better when Jobs go final instead of silent freezing.