Improved typing

src/common/graph/graph.ts

@@ -183,7 +183,7 @@ export class Graph
         this.idToNode.set(node.id, node);
     }
 
-    public createNode(data?: NodeData): Node {
+    public createNode(data?: NodeData | SimNodeData): Node {
         const node = new Node(this);
         node.fromSerializedObject(data);
         node.type = this.nameToObjectGroup.get(data.type);