My files

ClientInfo.js

import * as React from 'react'
import store from './InfoStore'
import { observer } from 'mobx-react'

import Paper from 'material-ui/Paper' 

const styles = require('../../../endpoint/css/DetailPage.css')

export default observer(({ header }) => 
  <Paper className={styles.infoGrid}>
    <h2 className={styles.gridHeader}>{header}</h2>
    <p className={styles.gridText}>{store.text}</p>
  </Paper>
) 

DetailsPage.js

import * as React from 'react'
import Loading from '../../helpers/Loading'
import { observer } from 'mobx-react'
import ClientInfo from './ClientInfo'
import HistoryGrid from './history/HistoryGrid'
import store from './InfoStore'
import ErrorMessage from '../../helpers/ErrorMessage'

const styles = require('../../../endpoint/css/DetailPage.css')

import Paper from 'material-ui/Paper'

export default observer(() =>
  <Paper className={styles.mainScreenWrapper}>
    <ClientInfo header='Client History'/>
    <ErrorMessage store={store}/>
    { store.loading ? <Loading/> : <HistoryGrid className={styles.historyGrid}/> }
  </Paper>)

Index.tsx

import * as React from 'react'
import * as ReactDOM from 'react-dom'
import * as injectTapEventPlugin from 'react-tap-event-plugin'
import DetailsPage from './bundles/details/DetailsPage'

// this is only the relevant parts

stacktrace

index.js:151 Uncaught TypeError: Cannot read property 'render' of undefined
observer @ index.js:151
(anonymous function) @ ClientInfo.js:9
__webpack_require__ @ bootstrap 29962d7…:555
fn @ bootstrap 29962d7…:86
(anonymous function) @ DetailsPage.js:4
__webpack_require__ @ bootstrap 29962d7…:555
fn @ bootstrap 29962d7…:86
(anonymous function) @ Index.tsx:4
__webpack_require__ @ bootstrap 29962d7…:555
fn @ bootstrap 29962d7…:86
(anonymous function) @ bootstrap 29962d7…:578
__webpack_require__ @ bootstrap 29962d7…:555
(anonymous function) @ bootstrap 29962d7…:578
(anonymous function) @ bootstrap 29962d7…:578
client.js:55[HMR] connected

tsconfig.json

{
    "compilerOptions": {
        "target": "ES6",
        "allowJs": true,
        "experimentalDecorators": true,
        "module": "commonjs",
        "removeComments": true,
        "jsx": "react"
    },
    "exclude": [
        "node_modules"
    ]
}

webpack.config.js

var path = require('path')
var webpack = require('webpack')
var ExtractTextPlugin = require('extract-text-webpack-plugin')

module.exports = {
  devtool: 'source-map',
  entry: [
    'webpack-hot-middleware/client',
    './src/app/Index.tsx'
  ],
  output: {
    path: __dirname + '/src/endpoint/static',
    filename: 'app.js',
    publicPath: '/static/'

  },
  plugins: [
    new ExtractTextPlugin('style.css', { allChunks: true }),
    new webpack.HotModuleReplacementPlugin(),
    new webpack.NoErrorsPlugin()
  ],
  resolve: {
    extensions: ['', '.ts', '.tsx', '.js']
  },
  module: {
    loaders: [{
      test: /\.ts$/,
      loaders: ['awesome-typescript-loader']
    },{
      test: /\.tsx$/,
      loaders: ['awesome-typescript-loader']
    },{
      test: /\.js$/,
      loaders: ['awesome-typescript-loader'],
      exclude: /node_modules/
    },{ 
      test: /\.css$/, 
      loader: 'style!css-loader?modules&importLoaders=1&localIdentName=[name]__[local]___[hash:base64:5]' 
    }]
  }
}