Clean up

src/Artemis.Core/VisualScripting/Interfaces/INode.cs

@@ -16,9 +16,9 @@ public interface INode : INotifyPropertyChanged, IBreakableModel
     Guid Id { get; set; }
     
     /// <summary>
-    /// Gets
+    ///     Gets or sets the node data with information about this node
     /// </summary>
-    NodeData NodeData { get; set; }
+    NodeData? NodeData { get; set; }
 
     /// <summary>
     ///     Gets the name of the node

src/Artemis.Core/VisualScripting/Nodes/Node.cs

@@ -42,7 +42,7 @@ public abstract class Node : BreakableModel, INode
     }
 
     /// <inheritdoc />
-    public NodeData NodeData { get; set; }
+    public NodeData? NodeData { get; set; }
 
     private string _name;
 

src/Artemis.Core/VisualScripting/Nodes/NodeTStorageTViewModel.cs

@@ -25,6 +25,8 @@ public abstract class Node<TStorage, TViewModel> : Node<TStorage>, ICustomViewMo
     /// <param name="nodeScript"></param>
     public virtual TViewModel GetViewModel(NodeScript nodeScript)
     {
+        if (NodeData == null)
+            throw new ArtemisCoreException("Nodes without node data (default nodes or exit nodes) cannot have custom view models");
         return NodeData.Provider.Plugin.Container.Resolve<TViewModel>(args: new object[] {this, nodeScript});
     }