Randomly meet Contact collider error? Really Need Help

Hi there,

I am stuck with problem contact error, In my game have enemy & gem collide with hero. But when I test some error contact collider return null randomly and show log message link below:
sometime collider A is null and sometime is collider B is null.

Simulator: /Applications/CocosCreator.app/Contents/Resources/cocos2d-x/simulator/mac/Simulator.app/Contents/Resources/src/jsb_polyfill.js:18424:TypeError: colliderB is null.

Do anybody know what is the problem? and how to fix it?

sincerely.