- add null check to TerrainLodControl

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9821 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/terrain/com/jme3/terrain/geomipmap/TerrainLodControl.java

@@ -201,6 +201,9 @@ public class TerrainLodControl extends AbstractControl {
     
     protected void prepareTerrain() {
         TerrainQuad terrain = (TerrainQuad)getSpatial();
+        if(terrain == null){
+            return;
+        }
         terrain.cacheTerrainTransforms();// cache the terrain's world transforms so they can be accessed on the separate thread safely
     }