Fix #550

jme3-core/src/main/java/com/jme3/scene/GeometryGroupNode.java

@@ -9,9 +9,6 @@ package com.jme3.scene;
 public abstract class GeometryGroupNode extends Node {
     
     public static int getGeometryStartIndex(Geometry geom) {
-        if (geom.startIndex == -1) {
-            throw new AssertionError();
-        }
         return geom.startIndex;
     }