--- upstream/assets\javascript\module\Aliens.js
+++ browser/assets\javascript\module\Aliens.js
@@ -101,8 +101,10 @@
             
             if(alien.health == 0){
                 _explosion = _explosionGroup.getFirstExists(false);
-                _explosion.reset(alien.body.x,alien.body.y);
+                if (_explosion) {
+                    _explosion.reset(alien.body.x,alien.body.y);
                 _explosion.play('kaboom',30,false,true);
+                }
             }
 
             HUD.updateScoreText(alien.myScore);
--- upstream/assets\javascript\module\Player.js
+++ browser/assets\javascript\module\Player.js
@@ -43,8 +43,10 @@
         if(ship.health == 0){            
             this.stopShooting();
             _explosion = _explosionGroup.getFirstExists(false);
-            _explosion.reset(_ship.body.x,_ship.body.y);
+            if (_explosion) {
+                _explosion.reset(_ship.body.x,_ship.body.y);
             _explosion.play('kaboom',30,false,true);
+            }
             
             _lives--;
             HUD.updateLivesText(_lives);