The javascript code will return null when there are no errors, but I'd

prefer to have an empty map returned in java land; so check for that and
do the right thing.

@@ -68,8 +68,12 @@ public class Require {
         NativeObject r = container.call(modelInstance, "toJSON", container.javaToJS(extraOptions));
         System.err.printf("r[%s]=%s\n", moduleId, container.toMap(r));
         NativeObject errors = RhinoContainer.allowUndefined(container.call(modelInstance, "validate"));
+        if (errors == null) {
+            return new HashMap<String, Object>();
+        } else {
             return new HashMap<String, Object>(errors);
         }
+    }
 
     public static class Loader extends InContext<Function> {
         private final RhinoContainer<?> container;