added the backgroundmusic to listeners in the initsimpleapp

and not in the getter of backgroundmusic.

Projekte/battleship/client/src/main/java/pp/battleship/client/BattleshipApp.java

@@ -238,6 +238,7 @@ public void simpleInitApp() {
 
         mainVolume = new MainVolume(this);
         backgroundMusic = new BackgroundMusic(this);
+        logic.addListener(backgroundMusic);
     }
 
     /**
@@ -446,7 +447,6 @@ void errorDialog(String errorMessage) {
      * @return BackgroundMusic
      */
     public BackgroundMusic getBackgroundMusic(){
-        logic.addListener(backgroundMusic);
         return backgroundMusic;
     }