title: "npm install" gives error message "invalid", what is it?
body: <p><a href="https://i.stack.imgur.com/0HmUZ.png" rel="noreferrer"><img src="https://i.stack.imgur.com/0HmUZ.png" alt="enter image description here"></a></p>
  
  <p>Please check the picture.</p>
  
  <p>I guess it's related to <code>package.json</code> but am not very sure.</p>
  
  <hr>
  
  <p><strong>Replying to the comment for more information</strong></p>
  
  <p>Initially I was installing <code>material-ui</code>.</p>
  
  <p>The detailed messages are here:</p>
  
  <blockquote>
    <p>I:\react-boilerplate>npm install material-ui</p>
    
    <p>react-boilerplate@3.4.0 I:\react-boilerplate</p>
    
    <p>+-- material-ui@0.17.1 </p>
    
    <p>| +-- keycode@2.1.8 </p>
    
    <p>| +-- lodash.throttle@4.1.1 </p>
    
    <p>| +-- UNMET PEER DEPENDENCY react@^15.4.2 </p>
    
    <p>| +-- react-addons-create-fragment@15.4.2 </p>
    
    <p>| +-- react-addons-transition-group@15.4.2 </p>
    
    <p>| +-- react-event-listener@0.4.3</p>
    
    <p>| | +-- UNMET PEER DEPENDENCY react@^15.4.2 </p>
    
    <p>| | `-- react-addons-shallow-compare@15.4.2 </p>
    
    <p>| +-- recompose@0.22.0 </p>
    
    <p>| | `-- change-emitter@0.1.3 </p>
    
    <p>| `-- simple-assign@0.1.0</p>
    
    <p>+-- UNMET PEER DEPENDENCY react-tap-event-plugin@^2.0.1 </p>
    
    <p>`-- UNMET PEER DEPENDENCY webpack@2.2.0-rc.3</p>
  </blockquote>
  
  <p>Then I was trying to fix the UNMET PEER DEPENDENCY by <code>npm install</code> them.</p>
  
  <p>The first attempt gives this:</p>
  
  <blockquote>
    <p>react-boilerplate@3.4.0 I:\react-boilerplate</p>
    
    <p>+-- react@15.4.2  invalid</p>
    
    <p>+-- react-tap-event-plugin@2.0.1 </p>
    
    <p>`-- UNMET PEER DEPENDENCY webpack@2.2.0-rc.3</p>
    
    <p>`-- webpack-sources@0.1.5</p>
  </blockquote>
  
  <p>As you can see this is the first <code>invalid</code> I met.</p>
  
  <p>So I'm just trying to figure out why this <code>invalid</code> pops out and how to fix it.</p>
  
  <hr>
  
  <p><strong>Replying to the comment for more information</strong></p>
  
  <p>Here is the package.json, dependencies section</p>
  
  <blockquote>
    <p>"dependencies": {
        "babel-polyfill": "6.20.0",
        "chalk": "1.1.3",
        "compression": "1.6.2",
        "cross-env": "3.1.3",
        "express": "4.14.0",
        "fontfaceobserver": "2.0.7",
        "immutable": "3.8.1",
        "intl": "1.2.5",
        "invariant": "2.2.2",
        "ip": "1.1.4",
        "lodash": "4.17.2",
        "minimist": "1.2.0",
        "react": "15.4.1",
        "react-dom": "15.4.1",
        "react-helmet": "3.2.2",
        "react-intl": "2.1.5",
        "react-redux": "4.4.6",
        "react-router": "3.0.0",
        "react-router-redux": "4.0.6",
        "react-router-scroll": "0.4.1",
        "redux": "3.6.0",
        "redux-immutable": "3.0.8",
        "redux-saga": "0.14.0",
        "reselect": "2.5.4",
        "sanitize.css": "4.1.0",
        "styled-components": "1.1.2",
        "warning": "3.0.0",
        "whatwg-fetch": "2.0.1"   },</p>
  </blockquote>
  
  <p>and the devDependencies section</p>
  
  <blockquote>
    <p>"devDependencies": {
        "babel-cli": "6.18.0",
        "babel-core": "6.21.0",
        "babel-eslint": "7.1.1",
        "babel-loader": "6.2.10",
        "babel-plugin-dynamic-import-node": "1.0.0",
        "babel-plugin-react-intl": "2.2.0",
        "babel-plugin-react-transform": "2.0.2",
        "babel-plugin-transform-es2015-modules-commonjs": "6.18.0",
        "babel-plugin-transform-react-constant-elements": "6.9.1",
        "babel-plugin-transform-react-inline-elements": "6.8.0",
        "babel-plugin-transform-react-remove-prop-types": "0.2.11",
        "babel-preset-latest": "6.16.0",
        "babel-preset-react": "6.16.0",
        "babel-preset-react-hmre": "1.1.1",
        "babel-preset-stage-0": "6.16.0",
        "cheerio": "0.22.0",
        "circular-dependency-plugin": "2.0.0",
        "coveralls": "2.11.15",
        "css-loader": "0.26.1",
        "enzyme": "2.6.0",
        "eslint": "3.11.1",
        "eslint-config-airbnb": "13.0.0",
        "eslint-config-airbnb-base": "10.0.1",
        "eslint-import-resolver-webpack": "0.8.0",
        "eslint-plugin-import": "2.2.0",
        "eslint-plugin-jsx-a11y": "2.2.3",
        "eslint-plugin-react": "6.7.1",
        "eslint-plugin-redux-saga": "0.1.5",
        "eventsource-polyfill": "0.9.6",
        "exports-loader": "0.6.3",
        "file-loader": "0.9.0",
        "html-loader": "0.4.4",
        "html-webpack-plugin": "2.24.1",
        "image-webpack-loader": "2.0.0",
        "imports-loader": "0.6.5",
        "jest-cli": "18.0.0",
        "lint-staged": "3.2.1",
        "ngrok": "2.2.4",
        "node-plop": "0.5.4",
        "null-loader": "0.1.1",
        "offline-plugin": "4.5.2",
        "plop": "1.7.3",
        "pre-commit": "1.1.3",
        "react-addons-test-utils": "15.4.1",
        "rimraf": "2.5.4",
        "shelljs": "0.7.5",
        "sinon": "2.0.0-pre",
        "style-loader": "0.13.1",
        "url-loader": "0.5.7",
        "webpack": "2.2.0-rc.3",
        "webpack-dev-middleware": "1.9.0",
        "webpack-hot-middleware": "2.15.0"   }</p>
  </blockquote>