Express doesn't load React's bundel.js, what's wrong?

Question

Express.js

After running Express, the front-end does not load and the error "Uncaught SyntaxError: Unexpected token <" is displayed in the console.
Please tell me what is wrong!
I load the frontend in this way:
app.use(express.static('./client'));
Here is my webpack config:

var webpack = require('webpack');
var path = require('path');

module.exports = {
    devtool: "source-map"
    entry: "./client/main.js",
    output: {
        path: path.resolve(__dirname, 'public/build'),
        filename: 'bundle.js'
    },
    module: {
        loaders: [
            {
                test: /\.js$/,
                exclude: [/node_modules/, /public/],
                loader: 'babel',
                query: {
                  presets:['es2015', 'react']
                }
            },
            {
                test: /\.jsx$/,
                exclude: [/node_modules/, /public/],
                loader: 'babel',
                query: {
                  presets:['es2015', 'react']
                }
            },
            {
              test: /\.css$/,
              exclude: [/node_modules/, /public/],
              loaders: ['style', 'css']
            },
            {
              test: /\.scss$/,
              exclude: [/node_modules/],
              loaders: ["style", "css?sourceMap", "sass?sourceMap"]
            }
        ]
    }
}

Answer 1

You most likely specified the wrong path to the file. Read more here (read the whole section, it's short).