title: NPM WARN: bootstrap@4.0.0 requires a peer of popper.js
body: <p>I have follow dependency part in package.json:  </p>
  
  <pre><code>"dependencies": {
      "bootstrap": "*",
      "bootstrap-datepicker": "^1.7.1",
      "bower": "^1.8.2",
      "chosen-js": "^1.8.2",
      "datatables.net-dt": "^1.10.16",
      "jQuery-QueryBuilder": "^2.4.5",
      "jquery": "^1.4",
      "jquery-tagit": "*",
      "jquery-ui-dist": "^1.12.1",
      "prismjs": "^1.8.1",
      "qtip2": "^3.0.3",
      "multi-step-modal": 
          "git+ssh://git@git.ias.su:2022/dependencies/multi-step-modal.git"
  }
  </code></pre>
  
  <p>When I run <code>npm update</code>, I get:  </p>
  
  <pre><code>LPS@1.0.0 /home/opshenichnikova/NetBeansProjects/lps/public
  ├── bootstrap@4.0.0 
  ├── jQuery-QueryBuilder@2.5.0 
  ├── multi-step-modal@1.0.0  (git+ssh://git@git.ias.su:2022/dependencies/multi-step-modal.git#2f9bc29093c9939c2ba23fa18fd22001a74040d2)
  ├── UNMET PEER DEPENDENCY popper.js@^1.12.9
  └── prismjs@1.12.2 
  
  npm WARN bootstrap@4.0.0 requires a peer of popper.js@^1.12.9 but none was installed.
  </code></pre>
  
  <p>I searched for the reason and found just this: <a href="https://stackoverflow.com/questions/46952775/bootstrap-4-uncaught-referenceerror-popper-is-not-defined">Bootstrap 4: Uncaught ReferenceError: Popper is not defined</a>  </p>
  
  <p>I know that it is just warning, but I always keep my code warning-free.</p>