title: npm ci outputs errors with angular 8 and node 12 on Windows: node-gyp rebuild
body: <p>My setup:</p>
  
  <ul>
  <li>Windows 10</li>
  <li>NVM 1.1.7 for Windows</li>
  <li>node 12.14.1 with npm 6.13.4</li>
  <li>Angular 8.2.14 with @angular/cli 8.3.22</li>
  </ul>
  
  <p>Just trying to run the default angular template:</p>
  
  <pre class="lang-sh prettyprint-override"><code>&gt; npm install -g @angular/cli # this installed the angular version mentioned above
  &gt; ng new test # Chose default options for the project
  &gt; cd test
  &gt; npm ci # lots of error messages
  </code></pre>
  
  <p>The last command results in lots of errors in the output (but does not fail the command):</p>
  
  <pre><code>&gt; fsevents@1.2.11 install C:\test\node_modules\@angular\compiler-cli\node_modules\fsevents
  &gt; node-gyp rebuild
  
  
  C:\test\node_modules\@angular\compiler-cli\node_modules\fsevents&gt;if not defined npm_config_node_gyp (node "C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\npm-lifecycle\node-gyp-bin\\..\..\node_modules\node-gyp\bin\node-gyp.js" rebuild )  else (node "C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\bin\node-gyp.js" rebuild )
  gyp ERR! find Python
  gyp ERR! find Python Python is not set from command line or npm configuration
  gyp ERR! find Python Python is not set from environment variable PYTHON
  gyp ERR! find Python checking if "python" can be used
  gyp ERR! find Python - "python" is not in PATH or produced an error
  gyp ERR! find Python checking if "python2" can be used
  gyp ERR! find Python - "python2" is not in PATH or produced an error
  gyp ERR! find Python checking if "python3" can be used
  gyp ERR! find Python - "python3" is not in PATH or produced an error
  gyp ERR! find Python checking if the py launcher can be used to find Python 2
  gyp ERR! find Python - "py.exe" is not in PATH or produced an error
  gyp ERR! find Python checking if Python is C:\Python27\python.exe
  gyp ERR! find Python - "C:\Python27\python.exe" could not be run
  gyp ERR! find Python checking if Python is C:\Python37\python.exe
  gyp ERR! find Python - "C:\Python37\python.exe" could not be run
  gyp ERR! find Python
  gyp ERR! find Python **********************************************************
  gyp ERR! find Python You need to install the latest version of Python.
  gyp ERR! find Python Node-gyp should be able to find and use Python. If not,
  gyp ERR! find Python you can try one of the following options:
  gyp ERR! find Python - Use the switch --python="C:\Path\To\python.exe"
  gyp ERR! find Python   (accepted by both node-gyp and npm)
  gyp ERR! find Python - Set the environment variable PYTHON
  gyp ERR! find Python - Set the npm configuration variable python:
  gyp ERR! find Python   npm config set python "C:\Path\To\python.exe"
  gyp ERR! find Python For more information consult the documentation at:
  gyp ERR! find Python https://github.com/nodejs/node-gyp#installation
  gyp ERR! find Python **********************************************************
  gyp ERR! find Python
  gyp ERR! configure error
  gyp ERR! stack Error: Could not find any Python installation to use
  gyp ERR! stack     at PythonFinder.fail (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:307:47)
  gyp ERR! stack     at PythonFinder.runChecks (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:136:21)
  gyp ERR! stack     at PythonFinder.&lt;anonymous&gt; (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:225:16)
  gyp ERR! stack     at PythonFinder.execFileCallback (C:\Users\foo\AppData\Roaming\nvm\v12.14.1\node_modules\npm\node_modules\node-gyp\lib\find-python.js:271:16)
  gyp ERR! stack     at exithandler (child_process.js:302:5)
  gyp ERR! stack     at ChildProcess.errorhandler (child_process.js:314:5)
  gyp ERR! stack     at ChildProcess.emit (events.js:223:5)
  gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:270:12)
  gyp ERR! stack     at onErrorNT (internal/child_process.js:456:16)
  gyp ERR! stack     at processTicksAndRejections (internal/process/task_queues.js:81:21)
  gyp ERR! System Windows_NT 10.0.18362
  gyp ERR! command "C:\\Program Files\\nodejs\\node.exe" "C:\\Users\\foo\\AppData\\Roaming\\nvm\\v12.14.1\\node_modules\\npm\\node_modules\\node-gyp\\bin\\node-gyp.js" "rebuild"
  gyp ERR! cwd C:\Users\foo\repos\POC\angular\test1\node_modules\@angular\compiler-cli\node_modules\fsevents
  gyp ERR! node -v v12.14.1
  gyp ERR! node-gyp -v v5.0.5
  gyp ERR!
  </code></pre>
  
  <p>All errors are related to <code>fsevents</code>, <code>node-gyp</code> and python executable not being found. That's right, I don't have python installed, but it's not a prerequisite for angular.</p>
  
  <p>The command actually exits with a 0 code (indicating success - besides, <code>ng build --prod</code> works after that!) but there surely are a lot of errors in the output.</p>
  
  <p>Deleting the <code>node_modules</code> folder manually and running <code>npm install</code> instead of <code>npm ci</code> produces an output which is a lot shorter and without any error. Also, it does not modify the <code>package-lock.json</code> file, which indicates that the same versions of the dependencies are installed.</p>
  
  <p>What is going on? Why so many errors when using <code>npm ci</code> but none when using <code>npm install</code>?</p>