webpack引用没有变量的类型

Question

运行

yarn run webpack:dev`

没问题，但是

yarn run webpack:prod: 

产生此错误：

 ERROR in Illegal State: referring to a type without a variable
{"filePath":"E:/****/node_modules/ng-zorro-antd/antd.d.ts","name":"ɵet","members":[]}

“ @ angular / animations”：“ 6.0.0”，     “ @ angular / common”：“ 6.0.0”，     “ @ angular / compiler”：“ 6.0.0”，     “ @ angular / core”：“ 6.0.0”，     “ @ angular / forms”：“ 6.0.0”，     “ @ angular / platform-b​​rowser”：“ 6.0.0”，     “ @ angular / platform-b​​rowser-dynamic”：“ 6.0.0”，     “ @ angular / router”：“ 6.0.0”，