Express.static لا يعمل

لدي الكود التالي

var express = require('express');
var webpack = require('webpack');
var app = express();

//app.use(express.static(path.join(__dirname, "public")));
app.use("/", express.static(__dirname + "/public"));
//both not working. I have tried multiple ways....

app.get("/",function (req, res){
res.sendFile(__dirname + "/public/index/index.html")
});


app.listen(3000);

Webpack configs

module.exports = {
entry: './app/index/index.js',
output: {
    path: path.resolve(__dirname, 'public/index'),
    publicPath: '/public/index',
    filename: 'index_bundle.js'
},
module: {
    rules: [
        { test: /\.(js)$/, use: 'babel-loader' },
        { test: /\.css$/, use: [ 'style-loader', 'css-loader' ]}
    ]
},
plugins: [
    new HtmlWebpackPlugin({
        template: 'app/index/index.html'
    })
]};

هيكلية الملفات

-public
        -index
          -index_bundle.js

يظهر لي الخطأ التالي عندما أحاول تحميل index_bundle.js:

GET http://localhost:3000/public/index/index_bundle.js 404 (Not Found)

كيف أحل المشكلة؟