fix: ensure paths + make html optional

Author: yyx990803

packages/@vue/cli-service/lib/commands/serve.js

@@ -60,11 +60,11 @@ module.exports = (api, options) => {
       if (!isProduction) {
         const devClients = [
           // dev server client
-          `webpack-dev-server/client/?${urls.localUrlForBrowser}`,
+          require.resolve(`webpack-dev-server/client`) + `?${urls.localUrlForBrowser}`,
           // hmr client
-          projectDevServerOptions.hotOnly
+          require.resolve(projectDevServerOptions.hotOnly
             ? 'webpack/hot/only-dev-server'
-            : 'webpack/hot/dev-server'
+            : 'webpack/hot/dev-server')
           // TODO custom overlay client
           // `@vue/cli-overlay/dist/client`
         ]

packages/@vue/cli-service/lib/config/base.js

@@ -1,5 +1,6 @@
 module.exports = (api, options) => {
   api.chainWebpack(webpackConfig => {
+    const fs = require('fs')
     const resolveLocal = require('../util/resolveLocal')
     const resolveClientEnv = require('../util/resolveClientEnv')
 
@@ -98,11 +99,12 @@ module.exports = (api, options) => {
         child_process: 'empty'
       })
 
+    const htmlPath = api.resolve('public/index.html')
     webpackConfig
       .plugin('html')
-        .use(require('html-webpack-plugin'), [{
-          template: api.resolve('public/index.html')
-        }])
+        .use(require('html-webpack-plugin'), [
+          fs.existsSync(htmlPath) ? { template: htmlPath } : {}
+        ])
 
     // inject preload/prefetch to HTML
     const PreloadPlugin = require('../webpack/PreloadPlugin')