title: "Already up-to-date" and "Run 'yarn' to install missing dependencies"?
body: <p>I've got a bit of a weird situation where "<em>ember s</em>" reports "<em>Missing yarn packages</em>" followed by a list of missing packages (two of them) and then "<em>Run 'yarn' to install missing dependencies</em>".</p>
  
  <p>However when I run '<em>yarn</em>' I get the message "<em>success Already up-to-date</em>" .</p>
  
  <p>Any ideas how to get out of this circle ?</p>
  
  <hr>
  
  <p>There's something I did immediately before this started which I guess is the source of my problem</p>
  
  <p><strong>Getting rid of an Add-on</strong></p>
  
  <p>I had installed an Ember Add-on which had generated problems so I decided to get rid of it . To do that I did the following :</p>
  
  <pre><code>git push -f origin 913c2dee12b0363df0664c9c63e0443abe0adb57:foo-bar
  git reset --hard 913c2dee12b0363df0664c9c63e0443abe0adb57
  yarn
  yarn install
  yarn clean
  yarn install
  yarn
  </code></pre>
  
  <p>Where 913c2dee12b0363df0664c9c63e0443abe0adb57 was the last commit before the unwanted add-on was installed. I don't think there was anything wrong in doing that but now I'm wondering.</p>
  
  <hr>
  
  <p><strong>Output of running Ember Server</strong></p>
  
  <p>When I run 'ember s' I get this output ...</p>
  
  <pre><code>DEPRECATION: ember-cli-babel 5.x has been deprecated. Please upgrade to at least ember-cli-babel 6.6. Version 5.2.8 located: foobar -&gt; ember-cli-build-date -&gt; ember-cli-babel
  
  Missing yarn packages:
  Package: @bower_components/jquery
    * Specified: jquery/jquery-dist#
    * Installed: (not installed)
  
  Package: @bower_components/jstree
    * Specified: vakata/jstree#^3.3.5
    * Installed: (not installed)
  
  Run `yarn` to install missing dependencies.
  
  
  
  Stack Trace and Error Report: /tmp/error.dump.33c6e8c0abc9fc8abd355dc080268f9c.log
  An error occurred in the constructor for ember-cli-dependency-checker at /media/mint/dev/foobar/node_modules/ember-cli-dependency-checker
  </code></pre>
  
  <hr>
  
  <p><strong>Warning about ember-cli versions</strong></p>
  
  <p>I don't think this is relevant but just for completeness</p>
  
  <p>Running the 'yarn' results in the following appearing in the output text ...</p>
  
  <p><em>warning foobar@0.0.0: "dependencies" has dependency "ember-cli" with range "~3.8.1" that collides with a dependency in "devDependencies" of the same name with version "3.8"</em></p>
  
  <hr>
  
  <p><strong>EDIT</strong>: OK I was able to resolve this with the help of the comment by dwenzel ...</p>
  
  <pre><code>rm -rf node_modules &amp;&amp; yarn
  </code></pre>
  
  <p>Although that actually led into a different issue which I'm <em>almost</em> certain was unrelated but I'll just mention it here in case it's useful to those who come after.</p>
  
  <p>The execution of <code>yarn</code> initially failed with the following error ...</p>
  
  <pre><code>35238 verbose stack Error: node-sass@4.5.3 postinstall: `node scripts/build.js`
  35238 verbose stack Exit status 1
  35238 verbose stack     at EventEmitter.&lt;anonymous&gt; (/home/rshea/.nvm/versions/node/v10.15.3/lib/node_modules/npm/node_modules/npm-lifecycle/index.js:301:16)
  35238 verbose stack     at EventEmitter.emit (events.js:189:13)
  35238 verbose stack     at ChildProcess.&lt;anonymous&gt; (/home/rshea/.nvm/versions/node/v10.15.3/lib/node_modules/npm/node_modules/npm-lifecycle/lib/spawn.js:55:14)
  35238 verbose stack     at ChildProcess.emit (events.js:189:13)
  35238 verbose stack     at maybeClose (internal/child_process.js:970:16)
  35238 verbose stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:259:5)
  35239 verbose pkgid node-sass@4.5.3
  35240 verbose cwd /media/mintextra/dev/ddn-build-test-temp/foobar
  35241 verbose Linux 3.13.0-169-generic
  35242 verbose argv "/home/rshea/.nvm/versions/node/v10.15.3/bin/node" "/home/rshea/.nvm/versions/node/v10.15.3/bin/npm" "install"
  35243 verbose node v10.15.3
  35244 verbose npm  v6.4.1
  35245 error code ELIFECYCLE
  35246 error errno 1
  35247 error node-sass@4.5.3 postinstall: `node scripts/build.js`
  35247 error Exit status 1
  35248 error Failed at the node-sass@4.5.3 postinstall script.
  35248 error This is probably not a problem with npm. There is likely additional logging output above.
  35249 verbose exit [ 1, true ]
  </code></pre>
  
  <p>I was able to resolve that with ...</p>
  
  <pre><code>npm install node-sass@latest
  npm install
  </code></pre>
  
  <p>... at which point <code>ember s</code> was able to run without errors.</p>