using webpack to create a new Vue project, Vue was introduced normally and worked, but when I introduced iview and tried to package it, I reported a lot of errors.
looked at it and found that css made a mistake:

webpack is configured as follows:

/*
  
*/
const path = require("path")
const webpack = require("webpack")
const HtmlWebpackPlugin = require("html-webpack-plugin")
const VueLoaderPlugin = require("vue-loader/lib/plugin")

module.exports = {
  entry: path.join(__dirname, "/src/main.js"),
  output: {
    path: path.join(__dirname, "/dist"),
    filename: "bundle.js"
  },
  module: {
    rules: [
      {
        test: /\.css$/,
        // use: ["style-loader", "css-loader"]
        // loader
        use: [
          {loader: "style-loader"},
          {loader: "css-loader"}
        ],
        exclude: /node_modules/
      },
      {
        test: /\.js$/,
        exclude: /node_modules/,
        loader: "babel-loader"
      },
      {
        test: /\.(png|jpg|svg|gif)$/,
        use: [
          {
            loader: "url-loader"
          }
        ]
      },
      {
        test: /\.vue$/,
        use: [
          {
            loader: "vue-loader"
          }
        ]
      }
    ]
  },
  plugins: [
    new webpack.HotModuleReplacementPlugin(),
    new HtmlWebpackPlugin({
      template: path.join(__dirname, "index.html")
    }),
    new VueLoaderPlugin()
  ],
  resolve: {
    alias: {
      "vue": "vue/dist/vue.js"
    }
  }
}

main.js

import Vue from "vue"
import iView from "iview"
import "iview/dist/styles/iview.css"
import App from "./App.vue"

Vue.use(iView)
new Vue({
  el: "-sharpapp",
  template: "<App/>",
  components: {App}
})

package.json:

{
  "name": "upload-manager",
  "version": "1.0.0",
  "description": "multi-media upload manager",
  "main": "main.js",
  "scripts": {
    "build": "webpack --config webpack.prod.js --progress --colors --mode production",
    "dev": "webpack-dev-server --open --config webpack.dev.js --progress --colors --mode development"
  },
  "author": "Yeoman_Li",
  "license": "ISC",
  "devDependencies": {
    "@babel/core": "^7.1.6",
    "@babel/preset-env": "^7.1.6",
    "autoprefix": "^1.0.1",
    "babel-core": "^6.26.3",
    "babel-loader": "^8.0.4",
    "babel-preset-env": "^1.7.0",
    "clean-webpack-plugin": "^1.0.0",
    "css-loader": "^1.0.1",
    "file-loader": "^2.0.0",
    "html-webpack-plugin": "^3.2.0",
    "iview": "^3.1.5",
    "style-loader": "^0.23.1",
    "url-loader": "^1.1.2",
    "vue": "^2.5.17",
    "vue-loader": "^15.4.2",
    "vue-template-compiler": "^2.5.17",
    "webpack": "^4.26.1",
    "webpack-cli": "^3.1.2",
    "webpack-dev-server": "^3.1.10",
    "webpack-merge": "^4.1.4"
  }
}