- revert previous change as wrong image paths might result

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@8001 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/niftygui/com/jme3/niftygui/NiftyJmeDisplay.java

@@ -75,7 +75,7 @@ public class NiftyJmeDisplay implements SceneProcessor {
             if (info != null){
                 return info.openStream();
             }else{
-                return null;
+                throw new AssetNotFoundException(path);
             }
         }