title: Getting error "PropTypes is not defined" in React
body: <p>Well, this code throws an error in console - "PropTypes is not defined", so application does not render. Any ideas what's wrong in configuration or even code? I am not using eslint if it matters btw.</p>
  
  <pre><code>import React, { Component } from 'react';
  import PropTypes from 'prop-types';
  
  export default class Movie extends Component {
    static propTypes = {
      movie: Proptypes.shape({
        title: Proptypes.string.isRequired
      })
    };
    static defaultProps = {
      description: 'Description is not available'
    }
    render() {
      return (
        &lt;div&gt;
          &lt;h3&gt;{this.props.movie.title}&lt;/h3&gt;
        &lt;/div&gt;
      )
    }
  }
  </code></pre>
  
  <p>However this works as expected(after component):</p>
  
  <pre><code>Movie.propTypes = {
    movie: PropTypes.shape({
      title: PropTypes.string.isRequired
    })
  }
  </code></pre>
  
  <p>package.json configuration:</p>
  
  <pre><code>{
    "dependencies": {
      "babel-polyfill": "^6.26.0",
      "live-server": "^1.2.0",
      "normalize.css": "^8.0.0",
      "prop-types": "^15.6.1",
      "react": "^16.2.0",
      "react-dom": "^16.2.0",
      "react-router-dom": "^4.2.2",
      "redux": "^3.7.2"
    },
    "devDependencies": {
      "babel-cli": "^6.26.0",
      "babel-core": "^6.26.0",
      "babel-loader": "^7.1.4",
      "babel-plugin-transform-class-properties": "^6.24.1",
      "babel-preset-env": "^1.6.1",
      "babel-preset-react": "^6.24.1",
      "babel-preset-stage-0": "^6.24.1",
      "css-loader": "^0.28.11",
      "node-sass": "^4.8.3",
      "sass-loader": "^6.0.7",
      "style-loader": "^0.20.3",
      "webpack": "^4.3.0",
      "webpack-cli": "^2.0.13"
    }
  }
  </code></pre>
  
  <p>.babelrc configuration:</p>
  
  <pre><code>{
    "presets": [
      "env",
      "react",
      "stage-0"
    ],
    "plugins": [
      "transform-class-properties"
    ]
  }
  </code></pre>
  
  <p>webpack.config.js </p>
  
  <pre><code>const path = require('path');
  
  module.exports = {
    entry: ['babel-polyfill','./src/app.js'],
    output: {
      path: path.join(__dirname, 'public'),
      filename: 'bundle.js'
    },
    module: {
      rules: [{
        loader: 'babel-loader',
        test: /\.js$/,
        exclude: /node_modules/,
        query: {
          presets: ['react', 'env', 'stage-3', 'stage-2', 'stage-1', 'stage-0']
        }
      }, {
        test: /\.s?css$/,
        use: [
          'style-loader',
          'css-loader',
          'sass-loader'
        ]
      }]
    },
    devtool: 'cheap-module-eval-source-map',
    devServer: {
      contentBase: path.join(__dirname, 'public'),
      historyApiFallback: true
    }
  };
  </code></pre>