Q:

Libgdx / Java Creating / Deleting Bodies creates Java log error

everytime I try to delete or create some bodies I get this error log here : 
http://pastebin.com/nTgsNdzZ
I delete / Create my bodies so : 
Delete : 
@Override
public void onDead() {

    super.onDead();

    /*
    attackTimer.cancel();
    attackTimer.purge();

    resetTimer.cancel();
    resetTimer.purge();
    */

    if(!game.hostServer && ! gameScreen.launcher.network.client.isConnected()){

        boolean spawned = false;

        while(!spawned){            

            int rdmChance = ThreadLocalRandom.current().nextInt(-2, 1 + 1);

            switch (rdmChance) {

            default : 

                spawned = true;

                break;

            case 1:

                HealthTank spawnedTank = new HealthTank(gameScreen, entityBody.getPosition());

                gameScreen.items.add(spawnedTank);

                spawned = true;

                break;

            }

        }

    }

    if(!gameScreen.lightManager.world.isLocked() && entityBody.getUserData() != null && entityBody != null ){

        entityBody.setUserData(null);

        activated = false;

        gameScreen.lightManager.world.destroyBody(entityBody);

    }

    removeNetworkEntity();

}

Create : 
public void randomizeSpawning(){

    int enemyCounter = 0;

    while(enemyCounter < enemyCount){

        int x = ThreadLocalRandom.current().nextInt(0, 49 + 1);
        int y = ThreadLocalRandom.current().nextInt(0, 49 + 1);

        if(game.grid[y][x] == 1 && SteeringUtils.distanz(new Vector2(x, y), new Vector2(gameScreen.playerEntity.getPosition().x, gameScreen.playerEntity.getPosition().y)) > 500){

               if(!gameScreen.lightManager.world.isLocked()){

                   Body body = gameScreen.createCircleBody(new Vector2(x*Box2dVars.UNIT,y*Box2dVars.UNIT), 20, 0);

                   EnemyEntity entity = new EnemyEntity(gameScreen, body);
                   entity.setUpBehaviors(gameScreen.playerEntity);

                   gameScreen.enemyEntityList.add(entity);

                   PacketMPMob mob = new PacketMPMob();
                   mob.listId = enemyCounter;
                   mob.id = gameScreen.launcher.network.client.getID();
                   mob.position = new Vector2(entity.getPosition().x * Box2dVars.UNIT, entity.getPosition().y * Box2dVars.UNIT);
                   mob.state = entity.getState();
                   mob.isAlive = true;

                   gameScreen.launcher.mobsList.add(enemyCounter, mob);

                   PacketAddMob addMob = new PacketAddMob();
                   addMob.id = gameScreen.launcher.network.client.getID();
                   addMob.listId = enemyCounter;
                   addMob.position = new Vector2(entity.getPosition().x * Box2dVars.UNIT, entity.getPosition().y * Box2dVars.UNIT);

                   System.err.println("POSITIONS : "+new Vector2(entity.getPosition().x * Box2dVars.UNIT, entity.getPosition().y * Box2dVars.UNIT));

                   gameScreen.launcher.network.client.sendTCP(addMob);

                   enemyCounter++;   

            }

        }

    }

}

What am I doing wrong?  I check if the world is locked and if than I'll create :/

A:

--Push--
Still no solution, also i just found out that this only appears, when i destroy a body and right after that spawn a new one

