问云函数报错Runtime.ImportModuleError:Cannot find module？

const { PurgeCSS } = require('purgecss'); 返回结果 {"errorCode":1,"errorMessage":"Runtime.ImportModuleError: Error: Cannot find module 'glob'\nRequire stack:\n- /var/user/purgecss.js\n- /var/user/index.js\n- /var/runtime/node14/UserFunction.js\n- /var/runtime/node14/Runtime.engine.js\n- /var/runtime/node14/bootstrap.js\n at Object.module.exports.load (/var/runtime/node14/UserFunction.js:34:13)\n at Runtime.handleOnce (/var/runtime/node14/Runtime.engine.js:85:38)\n at Timeout._onTimeout (/var/runtime/node14/Runtime.engine.js:54:12)\n at listOnTimeout (internal/timers.js:557:17)\n at processTimers (internal/timers.js:500:7)","requestId":"bb64c103-c704-42c7-8d3c-4fc05d1e8004","statusCode":443} 云函数SCF中如何导入npm包？