ARInterface support for 2018.1 beta?

I'm getting an error when building stock ARInterface samples for Android. They're working in 2017.3 without any of the Vuforia player settings checked. Has anyone found a work-around?

https://github.com/Unity-Technologies/experimental-ARInterface


TypeLoadException: Could not load type 'BuildObserver' from assembly 'Vuforia.UnityExtensions.Editor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'.
System.MonoType.GetConstructors (BindingFlags bindingAttr) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/MonoType.cs:134)
System.MonoType.GetConstructorImpl (BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/MonoType.cs:95)
System.Type.GetConstructor (BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Type.cs:1007)
System.MonoType.GetDefaultConstructor () (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/MonoType.cs:75)
System.Activator.CreateInstance (System.Type type, Boolean nonPublic) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Activator.cs:354)
System.Activator.CreateInstance (System.Type type) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Activator.cs:254)
UnityEditor.Build.BuildPipelineInterfaces.InitializeBuildCallbacks (BuildCallbacks findFlags) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/BuildPipelineInterfaces.cs:117)
UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr)