Reproduction steps:
1. Download user's project and open in Unity
2. Create Rendering -> DecalProjector in the scene

Expected: no errors in the console
Actual: error appears in the console

Reproduced on: 2018.1.0b10; 2018.1.0b13; 2018.2.0a8

Note:
Error message:
"NullReferenceException: Object reference not set to an instance of an object
UnityEngine.Experimental.Rendering.HDPipeline.DecalSystem.AddDecal (UnityEngine.Transform transform, Single drawDistance, Single fadeScale, UnityEngine.Material material) (at C:/ProgramData/Unity/cache/packages/packages.unity.com/com.unity.render-pipelines.high-definition@1.1.2-preview/HDRP/Decal/DecalSystem.cs:447)
UnityEngine.Experimental.Rendering.HDPipeline.DecalProjectorComponent.OnEnable () (at C:/ProgramData/Unity/cache/packages/packages.unity.com/com.unity.render-pipelines.high-definition@1.1.2-preview/HDRP/Decal/DecalProjectorComponent.cs:44)
UnityEditor.GenericMenu:CatchMenu(Object, String[], Int32)"
2018.1.0b9 does not have Rendering -> DecalProject