<p dir="auto">A simple reproduce repository: <a href="https://github.com/plantain-00/test">https://github.com/plantain-00/test</a> , after <code class="notranslate">npm i &amp;&amp; npm run build</code>, the error is:</p>
<div class="highlight highlight-source-ts notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="node_modules/@types/core-js/index.d.ts(21,14): error TS2300: Duplicate identifier 'PropertyKey'.
node_modules/typescript/lib/lib.es6.d.ts(4133,14): error TS2300: Duplicate identifier 'PropertyKey'."><pre class="notranslate"><span class="pl-s1">node_modules</span><span class="pl-c1">/</span>@<span class="pl-s1">types</span><span class="pl-pds"><span class="pl-c1">/</span>core-js<span class="pl-c1">/</span>index</span><span class="pl-kos">.</span><span class="pl-c1">d</span><span class="pl-kos">.</span><span class="pl-en">ts</span><span class="pl-kos">(</span><span class="pl-c1">21</span><span class="pl-kos">,</span><span class="pl-c1">14</span><span class="pl-kos">)</span>: <span class="pl-s1">error</span><span class="pl-kos"></span> <span class="pl-smi">TS2300</span>: <span class="pl-smi">Duplicate</span> <span class="pl-s1">identifier</span> <span class="pl-s">'PropertyKey'</span><span class="pl-kos">.</span>
<span class="pl-c1">node_modules</span><span class="pl-c1">/</span><span class="pl-s1">typescript</span><span class="pl-c1">/</span><span class="pl-s1">lib</span><span class="pl-c1">/</span><span class="pl-s1">lib</span><span class="pl-kos">.</span><span class="pl-c1">es6</span><span class="pl-kos">.</span><span class="pl-c1">d</span><span class="pl-kos">.</span><span class="pl-en">ts</span><span class="pl-kos">(</span><span class="pl-c1">4133</span><span class="pl-kos">,</span><span class="pl-c1">14</span><span class="pl-kos">)</span>: <span class="pl-s1">error</span> <span class="pl-smi">TS2300</span>: <span class="pl-smi">Duplicate</span> <span class="pl-s1">identifier</span> <span class="pl-s">'PropertyKey'</span><span class="pl-kos">.</span></pre></div>
<p dir="auto">Expected: no error, because the <code class="notranslate">app.ts</code> is empty. the <code class="notranslate">@types/core-js</code> is used in <code class="notranslate">static/app.ts</code>.</p>
<div class="highlight highlight-source-ts notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="  &quot;devDependencies&quot;: {
    &quot;@types/core-js&quot;: &quot;^0.9.34&quot;,
    &quot;core-js&quot;: &quot;^2.4.1&quot;,
    &quot;typescript&quot;: &quot;^2.0.3&quot;
  }"><pre class="notranslate">  <span class="pl-s">"devDependencies"</span>: <span class="pl-kos">{</span>
    <span class="pl-s">"@types/core-js"</span>: <span class="pl-s">"^0.9.34"</span><span class="pl-kos">,</span>
    <span class="pl-s">"core-js"</span>: <span class="pl-s">"^2.4.1"</span><span class="pl-kos">,</span>
    <span class="pl-s">"typescript"</span>: <span class="pl-s">"^2.0.3"</span>
  <span class="pl-kos">}</span></pre></div>
<p dir="auto">I'm using the version <code class="notranslate">4.41.7</code> of the package <code class="notranslate">@types/webpack</code>, and I think that is missing <a href="https://webpack.js.org/configuration/dev-server/" rel="nofollow"><code class="notranslate">devServer</code></a> type on <code class="notranslate">Configuration</code> interface.</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/9501115/77070925-1344f380-69e3-11ea-9b8c-804308899419.png"><img src="https://user-images.githubusercontent.com/9501115/77070925-1344f380-69e3-11ea-9b8c-804308899419.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto"><a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/tkqubo/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/tkqubo">@tkqubo</a><br>
<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/bumbleblym/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/bumbleblym">@bumbleblym</a><br>
<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/bcherny/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/bcherny">@bcherny</a><br>
<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/tommytroylin/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/tommytroylin">@tommytroylin</a><br>
<a class="user-mention notranslate" data-hovercard-type="user" data-hovercard-url="/users/mohsen1/hovercard" data-octo-click="hovercard-link-click" data-octo-dimensions="link_type:self" href="https://github.com/mohsen1">@mohsen1</a></p>