[LayaAir 2.0]多个文件之间相互import，运行时报错

大概就是子类 A import基类B，基类B import了另一个类C，C又import了子类A。。。
但是多个文件互相import在开发中不可避免啊，请问怎么解决呢？
 
 
TypeError: Object prototype may only be an Object or null: undefined
preload.js:55
at setPrototypeOf (<anonymous>)
 
at __extends (file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:6:9)
 
at file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:41201:5
 
at Object.172.../GameManager (file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:41206:2)
 
at o (file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:11:265)
 
at file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:11:316
 
at Object.100.../GameManager (file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:23311:13)
 
at o (file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:11:265)
 
at file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:11:316
 
at Object.16.../GameManager (file:///E:/SVN/ZQ2/client2.0/bin/js/bundle.js:4727:23)