Super expression must either be null or a function错误!

[a116 (dfsdfsg)]

export default class BulletAssembler extends cc.Assembler2D {

constructor() {
    super();
}

}

写个Assembler, 直接报错, 写不写super() 都报错.

//
引擎内部的:export default class MotionStreakAssembler extends Assembler2D 拖尾效果没写super() ，却不报错．