https://github.com/kisenka/svg-sprite-loader/issues/133

webpack.config.js

const path = require('path');
const webpack = require('webpack');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const SpriteLoaderPlugin = require('svg-sprite-loader/plugin');

module.exports = {
    entry: './src/index.js',
    output: {
        path: path.resolve(__dirname, '../dist'),
        filename: '[name].js'
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                exclude: /node_modules/,
                loader: 'babel-loader',
                options: {
                    presets: [
                        ['env', {
                            targets: {
                                uglify: true
                            }
                        }],
                        'react'
                    ],
                    plugins: ["transform-class-properties"]
                }
            },
            {
                test: /\.css$/,
                use: ExtractTextPlugin.extract({
                    use: [
                        'css-loader',
                        'svg-fill-loader/encodeSharp' // See https://www.npmjs.com/package/svg-fill-loader#using-with-css-loader
                    ]
                })
            },
            {
                test: /\.svg$/,
                exclude: /src\/fonts/,
                use: [
                    'svg-sprite-loader',
                    'svg-fill-loader',
                    'svgo-loader'
                ]
            },
            {
                test: /(\.(png|jpg|gif|woff|woff2|eot|ttf|otf)|\/src\/fonts\/.+\.svg)$/,
                loader: 'file-loader',
                options: {
                    name: '[name].[hash].[ext]'
                }
            }
        ]
    },
    plugins: [
        new ExtractTextPlugin('styles.css'),
        new SpriteLoaderPlugin(),
        new webpack.optimize.CommonsChunkPlugin({
            name: 'vendor',
            minChunks: function(module) {
                return module.context && ~module.context.indexOf('node_modules');
            }
        }),
        new webpack.optimize.CommonsChunkPlugin({
            name: 'manifest'
        }),
        new HtmlWebpackPlugin({
            template: 'pug-loader!src/index.pug'
        })
    ],
    resolve: {
        alias: {
            App: path.resolve(__dirname, '../src')
        }
    }
};