title: Bitbucket Pipelines error whilst building an application
body: <p>since this morning I'm encountering an error in the build process of my React application using Bitbucket Pipelines. Nothing has changed to my applications other than a few tweaks that has should not trigger this error. </p>
  
  <p>When I try to build my app locally I don't get any errors whatsoever. Beneath you can find the error NPM throws in Pipelines.</p>
  
  <pre><code>+ npm run build-debug
  npm info it worked if it ends with ok
  npm info using npm@2.15.9
  npm info using node@v4.6.0
  npm info prebuild-debug webplayer@0.1.2
  npm info build-debug webplayer@0.1.2
  &gt; webplayer@0.1.2 build-debug /opt/atlassian/pipelines/agent/build
  &gt; node scripts/build-debug.js
  Creating an optimized production build...
  Failed to compile.
  Module not found: Error: Cannot resolve module 'promise-polyfill' in /opt/atlassian/pipelines/agent/build/node_modules/firebase/app
  npm info webplayer@0.1.2 Failed to exec build-debug script
  npm ERR! Linux 4.9.16-coreos-r1
  npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "build-debug"
  npm ERR! node v4.6.0
  npm ERR! npm  v2.15.9
  npm ERR! code ELIFECYCLE
  npm ERR! webplayer@0.1.2 build-debug: `node scripts/build-debug.js`
  npm ERR! Exit status 1
  npm ERR! 
  npm ERR! Failed at the webplayer@0.1.2 build-debug script 'node scripts/build-debug.js'.
  npm ERR! This is most likely a problem with the webplayer package,
  npm ERR! not with npm itself.
  npm ERR! Tell the author that this fails on your system:
  npm ERR!     node scripts/build-debug.js
  npm ERR! You can get information on how to open an issue for this project with:
  npm ERR!     npm bugs webplayer
  npm ERR! Or if that isn't available, you can get their info via:
  npm ERR! 
  npm ERR!     npm owner ls webplayer
  npm ERR! There is likely additional logging output above.
  npm ERR! Please include the following file with any support request:
  npm ERR!     /opt/atlassian/pipelines/agent/build/npm-debug.log
  </code></pre>
  
  <p>Thanks in advance!</p>