Removed color for undefined node types.

display/graph.js

@@ -379,7 +379,6 @@ class Graph {
 
     mapNodeColors() {
         const nodeClasses = this.getNodeClasses();
-        this.nodeColors["undefined"] = Config.COLOR_PALETTE[0]; // Default color
         for (let i = 0; i < nodeClasses.length; i++) {
             this.nodeColors[nodeClasses[i]] =
                 Config.COLOR_PALETTE[i % Config.COLOR_PALETTE.length];