fix esm build exports

Author: yyx990803

build/dev-entry.js

@@ -3,7 +3,7 @@ const replace = require('rollup-plugin-replace')
 const version = process.env.VERSION || require('../package.json').version
 
 module.exports = {
-  entry: 'src/index.js',
+  entry: process.env.ESM ? 'src/index.esm.js' : 'src/index.js',
   dest: process.env.ESM ? 'dist/vuex.esm.js' : 'dist/vuex.js',
   format: process.env.ESM ? 'es' : 'umd',
   moduleName: 'Vuex',

build/rollup.config.js

@@ -32,7 +32,7 @@ module.exports = {
 
   resolve: {
     alias: {
-      vuex: path.resolve(__dirname, '../build/dev-entry')
+      vuex: path.resolve(__dirname, '../src/index.esm.js')
     }
   },
 

examples/webpack.config.js

@@ -0,0 +1,20 @@
+import { Store, install } from './store'
+import { mapState, mapMutations, mapGetters, mapActions } from './helpers'
+
+export default {
+  Store,
+  install,
+  version: '__VERSION__',
+  mapState,
+  mapMutations,
+  mapGetters,
+  mapActions
+}
+
+export {
+  Store,
+  mapState,
+  mapMutations,
+  mapGetters,
+  mapActions
+}