<p dir="auto">Does nextJS provide sourcemaps for dev? I added a debugger statement to my code and when It breaks in console, it just shows null as my code.</p>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://camo.githubusercontent.com/1238267ff8cdc1b42cdeeb8156341031208ee86c09b5f5d0d9575bc61a08a48d/687474703a2f2f692e696d6775722e636f6d2f4c687645624e6a2e706e67"><img src="https://camo.githubusercontent.com/1238267ff8cdc1b42cdeeb8156341031208ee86c09b5f5d0d9575bc61a08a48d/687474703a2f2f692e696d6775722e636f6d2f4c687645624e6a2e706e67" alt="issue" data-canonical-src="http://i.imgur.com/LhvEbNj.png" style="max-width: 100%;"></a></p>


<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/zeit/next.js/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Expected Behavior</h2>


<p dir="auto">The sourcemap should be used and my actual code should show</p>
<h2 dir="auto">Current Behavior</h2>


<p dir="auto">See above</p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>


<ol dir="auto">
<li></li>
<li></li>
<li></li>
<li></li>
</ol>
<h2 dir="auto">Context</h2>


<p dir="auto">Makes debugging really challenging</p>
<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>next</td>
<td>3.2.1</td>
</tr>
<tr>
<td>node</td>
<td>8.4.0</td>
</tr>
<tr>
<td>OS</td>
<td>Win 10 Pro</td>
</tr>
<tr>
<td>browser</td>
<td>Chrome Version 61</td>
</tr>
<tr>
<td>etc</td>
<td></td>
</tr>
</tbody>
</table>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/zeit/next.js/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Expected Behavior</h2>


<p dir="auto">I would expect to see the source map in the dev tools of Chrome.</p>
<h2 dir="auto">Current Behavior</h2>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/3165635/30108907-87174b90-9304-11e7-9bf4-1355d87fdc95.png"><img width="234" alt="capture d ecran 2017-09-06 a 13 08 18" src="https://user-images.githubusercontent.com/3165635/30108907-87174b90-9304-11e7-9bf4-1355d87fdc95.png" style="max-width: 100%;"></a></p>


<h2 dir="auto">Steps to Reproduce (for bugs)</h2>


<p dir="auto">With Material-UI:</p>
<ol dir="auto">
<li><code class="notranslate">git clone git@github.com:callemall/material-ui.git</code></li>
<li><code class="notranslate">cd material-ui</code></li>
<li><code class="notranslate">git checkout v1-beta</code></li>
<li><code class="notranslate">yarn</code></li>
<li><code class="notranslate">yarn docs:dev</code></li>
</ol>
<p dir="auto">Or with a simpler project: <a href="https://github.com/callemall/material-ui/tree/v1-beta/examples/nextjs">https://github.com/callemall/material-ui/tree/v1-beta/examples/nextjs</a>.</p>
<h2 dir="auto">Context</h2>
<ol dir="auto">
<li>I have first noticed this issue on a project at work.</li>
<li>Hopefully, I was able to nail down the npm release that introduced the issue <a href="https://github.com/callemall/material-ui/compare/v1.0.0-beta.6...v1.0.0-beta.7#diff-b9cfc7f2cdf78a7f4b91a753d10865a2L74">by a bisection between</a> the <code class="notranslate">v1.0.0-beta.6</code> release and <code class="notranslate">v1.0.0-beta.7</code> release of Material-UI.</li>
<li>I'm also able to reproduce the issue on a simpler example, the <a href="https://github.com/callemall/material-ui/tree/v1-beta/examples/nextjs">nextjs example</a> of Material-UI.</li>
</ol>
<p dir="auto">So, it's 3 independent projects impacted by the issue. I do think that it's a strong <a href="https://en.wikipedia.org/wiki/Signal-to-noise_ratio" rel="nofollow">SNR</a> ratio.</p>
<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>next</td>
<td>v3.2.1</td>
</tr>
<tr>
<td>node</td>
<td>v8.1.4</td>
</tr>
<tr>
<td>OS</td>
<td>MacOs</td>
</tr>
<tr>
<td>browser</td>
<td>Chrome</td>
</tr>
</tbody>
</table>