It’s been a while since I run NodeCanvas, just did a fresh import into Unity 2017.4.2f2 (and also spearately 2017.1).

There’s this error:
NullReferenceException: Object reference not set to an instance of an object
NodeCanvas.Editor.CanvasStyles.get_canvasBG () (at Assets/ParadoxNotion/NodeCanvas/Framework/Design/PartialEditor/CanvasStyles.cs:97)
NodeCanvas.Editor.GraphEditor.OnGUI () (at Assets/ParadoxNotion/NodeCanvas/Framework/Design/Editor/Windows/GraphEditor.cs:464)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.HostView.Invoke (System.String methodName, System.Object obj) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:295)
UnityEditor.HostView.Invoke (System.String methodName) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:288)
UnityEditor.HostView.InvokeOnGUI (Rect onGUIPosition) (at C:/buildslave/unity/build/Editor/Mono/HostView.cs:255)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Missing files?