我有一个meanjs应用程序，它在节点版本6上运行良好，但是在升级节点8时会引发很多错误 这样的错误
+ Error: NODE_ENV is not defined! Using default development environment
(node:3812) DeprecationWarning: current URL string parser is deprecated, and wil l be removed in a future version. To use the new parser, pass option { useNewUrl Parser: true } to MongoClient.connect.(node:3812) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejec
tion id: 1): Error: Connection strategy not found
(node:3812) [DEP0018] DeprecationWarning: Unhandled promise rejections are depre
cated. In the future, promise rejections that are not handled will terminate the
Node.js process with a non-zero exit code.