碰撞的时候经常会发生这种错误。然后无限报错下去
utils.js:5 Uncaught TypeError: Cannot read property 'parent' of null
at getWorldRotation (utils.js:5)
at cc_RigidBody.__init (CCRigidBody.js:906)
at CCClass.update (CCPhysicsManager.js:192)
at TheClass.update (CCScheduler.js:401)
at TheClass.mainLoop (CCDirector.js:1473)
at callback (CCGame.js:581)
