Mesh: avoid NPE in getMorphTargets() when there are no targets (#1231)

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

@@ -1527,8 +1527,12 @@ public class Mesh implements Savable, Cloneable, JmeCloneable {
     }
 
     public MorphTarget[] getMorphTargets() {
+        if (morphTargets == null) {
+            return new MorphTarget[0];
+        } else {
             return morphTargets.getArray();
         }
+    }
     
     /**
      * Get the name of all morphs in order.