TypeScipt + @storybook/vue + @vue/cli 構成用の Webpack 設定ファイル。@vue/cli@3.0.0-beta.10 + webpack@4.8.2 + vue-loader@15.0.10 でビルド確認済み。

webpack.config.js

const merge = require('webpack-merge');
const vueConfig = require('@vue/cli-service/webpack.config.js');

module.exports = (storybookConfig, configType) => {
  return {
    ...vueConfig, // use vue's webpack configuration by default
    entry: storybookConfig.entry, // overwite entry
    output: storybookConfig.output, // overwrite output
    // remove duplicated plugins
    plugins: merge({
      customizeArray: merge.unique(
        'plugins',
        ['HotModuleReplacementPlugin', 'CaseSensitivePathsPlugin', 'WatchMissingNodeModulesPlugin'],
        plugin => plugin.constructor && plugin.constructor.name,
      ),
    })(vueConfig, storybookConfig).plugins,
    resolve: {
      // <--------- This bit here
      ...vueConfig.resolve,
      alias: {
        ...vueConfig.resolve.alias,
        vue$: storybookConfig.resolve.alias.vue$,
      },
    },
  };
};

参考：almeynman/typescript-vue-storybook-tutorial