element-ui 启动失败

element-ui 使用 npm run dev 启动失败；错误信息是： PS C:\workspase\web> npm run dev

[email protected] dev C:\workspase\web vue-cli-service serve

INFO Starting development server... 10% building 2/2 modules 0 active ERROR SyntaxError: Cannot use import statement outside a module C:\workspase\web\mock\index.js:1 import "core-js/modules/es6.regexp.constructor"; at Server.setupAfterFeature (C:\workspase\web\node_modules\webpack-dev-server\lib\Server.js:439:18) at Object.after (C:\workspase\web\node_modules\webpack-dev-server\lib\Server.js:499:16) at C:\workspase\web\node_modules\webpack-dev-server\lib\Server.js:558:24 at Array.forEach (<anonymous>) at Server.setupFeatures (C:\workspase\web\node_modules\webpack-dev-server\lib\Server.js:557:49) at new Server (C:\workspase\web\node_modules\webpack-dev-server\lib\Server.js:133:10) npm ERR! code ELIFECYCLE npm ERR! errno 1 npm ERR! [email protected] dev: vue-cli-service serve npm ERR! Exit status 1 npm ERR! npm ERR! Failed at the [email protected] dev script. npm ERR! This is probably not a problem with npm. There is likely additional logging output above. 有大神遇到过这个问题吗？求解答</anonymous>