Steps to reproduce:
1. Create new Unity project using Universal 3D Template
2. Open Project Settings window
3. In Player > Other Settings > Script Compilation > Scripting Define Symbols add UNIFIED_BAKER symbol
4. Press Apply
5. Wait for compiling to finish
6. In Hierarchy window create Terrain GO (Terrain should automatically be set to Static)
7. Open Lighting window
8. Create new Lighting Settings Asset
9. In Lightmapping Settings > Lightmapper select > Unity Compute (GPU)
10. At the bottom of the window press "Generate Lighting"
11. Observe the Console window

Actual results: Light generation fails, errors are thrown in the Console window
Expected results: Light should be generated successfully without any errors thrown in the Console window

Reproducible with versions: 6000.4.0a1
Can’t test with versions: 6000.3.0b4 and lower (Unity Compute (GPU) not available)

Tested on (OS): Windows 11

Errors:
1. [Worker2] IndexOutOfRangeException: Index was outside the bounds of the array.
UnityEditor.PathTracing.LightBakerBridge.BakeInputToWorldConversion.ConvertInstancesAndMeshes (UnityEngine.PathTracing.Core.World world, UnityEditor.PathTracing.LightBakerBridge.BakeInput& bakeInput, UnityEngine.PathTracing.Core.Handle`1[UnityEngine.PathTracing.Core.World+MaterialDescriptor][][]& perInstanceSubMeshMaterials, System.Boolean[][]& perInstanceSubMeshVisibility, UnityEngine.Bounds& sceneBounds, UnityEngine.Mesh[]& meshes, UnityEngine.PathTracing.Lightmapping.FatInstance[]& fatInstances, System.Collections.Generic.List`1[T] allocatedObjects, System.UInt32 renderingObjectLayer) (at ./Library/PackageCache/com.unity.render-pipelines.core@942a815dc3c0/Editor/PathTracing/BakeInputToWorldConversion.cs:424)

2. [Worker2] Asset import failed, "Temp/LightBakerAssetImport/BakeImport.asset" > IndexOutOfRangeException: Index was outside the bounds of the array.
UnityEditor.PathTracing.LightBakerBridge.BakeInputToWorldConversion.ConvertInstancesAndMeshes (UnityEngine.PathTracing.Core.World world, UnityEditor.PathTracing.LightBakerBridge.BakeInput& bakeInput, UnityEngine.PathTracing.Core.Handle`1[UnityEngine.PathTracing.Core.World+MaterialDescriptor][][]& perInstanceSubMeshMaterials, System.Boolean[][]& perInstanceSubMeshVisibility, UnityEngine.Bounds& sceneBounds, UnityEngine.Mesh[]& meshes, UnityEngine.PathTracing.Lightmapping.FatInstance[]& fatInstances, System.Collections.Generic.List`1[T] allocatedObjects, System.UInt32 renderingObjectLayer) (at ./Library/PackageCache/com.unity.render-pipelines.core@942a815dc3c0/Editor/PathTracing/BakeInputToWorldConversion.cs:424)

3. [Worker2] NullReferenceException: Object reference not set to an instance of an object.
UnityEngine.Bindings.ThrowHelper.ThrowNullReferenceException (System.Object obj) (at <648afa66a7fd4d229465d3e0fcb34869>:0)
UnityEngine.LightTransport.BakeProgressState.WasCancelled () (at <648afa66a7fd4d229465d3e0fcb34869>:0)
UnityEditor.PathTracing.LightBakerBridge.LightBakerWorkerProcessImporter.ProgressReporterThreadFunction (UnityEditor.LightBaking.ExternalProcessConnection connection, System.Threading.CancellationToken bakeIsFinished, UnityEngine.LightTransport.BakeProgressState progressState) (at ./Library/PackageCache/com.unity.render-pipelines.core@942a815dc3c0/Editor/PathTracing/LightBakerWorkerProcessImporter.cs:103)
UnityEditor.PathTracing.LightBakerBridge.LightBakerWorkerProcessImporter+<>c__DisplayCla

4. Light baking failed with error code 2 (Failed to communicate with the worker process, it might have crashed).

5. Failed copying the texture from '.../PostProcessingOutput/lightmapRequest0/Lightmap-0_comp_light.exr' to 'Temp/GI/7db43aa4627103201baccaab3de8e56d/Lightmap-0_comp_light.exr'.