未捕获的ReferenceError：导出未定义为Vue + Webpack

Question

我正在尝试将Leaflet库源添加到我的项目中，但是我在语句中收到错误。

window.L = exports;

Vue Import Statement，传单文件夹的副本在我的项目src文件夹中

import L from '@/leaflet/src/Leaflet'

问题的截图。

我已经更新了vue，babel和webpack，但问题仍未解决，这是我的配置。

"dependencies": {
    "bootstrap": "^3.3.7",
    "jquery": "^3.3.1",
    "leaflet": "^1.3.1",
    "vue": "^2.5.2",
    "vue-resource": "^1.3.5",
    "vue-router": "^3.0.1",
    "vuex": "^3.0.1"
  },
  "devDependencies": {
    "autoprefixer": "^7.1.2",
    "babel-core": "^6.26.0",
    "babel-helper-vue-jsx-merge-props": "^2.0.3",
    "babel-loader": "^7.1.2",
    "babel-plugin-syntax-jsx": "^6.18.0",
    "babel-plugin-transform-es2015-modules-umd": "^6.24.1",
    "babel-plugin-transform-runtime": "^6.22.0",
    "babel-plugin-transform-vue-jsx": "^3.5.0",
    "babel-preset-env": "^1.6.1",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-stage-2": "^6.22.0",
    "chalk": "^2.0.1",
    "copy-webpack-plugin": "^4.0.1",
    "css-loader": "^0.28.0",
    "extract-text-webpack-plugin": "^3.0.0",
    "file-loader": "^1.1.4",
    "friendly-errors-webpack-plugin": "^1.6.1",
    "html-webpack-plugin": "^2.30.1",
    "node-notifier": "^5.1.2",
    "optimize-css-assets-webpack-plugin": "^3.2.0",
    "ora": "^1.2.0",
    "portfinder": "^1.0.13",
    "postcss-import": "^11.0.0",
    "postcss-loader": "^2.0.8",
    "rimraf": "^2.6.0",
    "semver": "^5.3.0",
    "shelljs": "^0.7.6",
    "uglifyjs-webpack-plugin": "^1.1.1",
    "url-loader": "^0.5.8",
    "vue-loader": "^13.3.0",
    "vue-style-loader": "^3.0.1",
    "vue-template-compiler": "^2.5.2",
    "webpack": "^3.10.0",
    "webpack-bundle-analyzer": "^2.9.0",
    "webpack-dev-server": "^2.9.1",
    "webpack-merge": "^4.1.0"
  }

.babelrc

{
  "presets": [
    ["env", {
      "modules": false,
      "targets": {
        "browsers": ["> 1%", "last 2 versions", "not ie <= 8"]
      }
    }],
    "stage-2"
  ],
  "plugins": ["transform-vue-jsx", "transform-runtime"]
}

谢谢