<p dir="auto">I tried to use  with <code class="notranslate">implementation=css</code> and <code class="notranslate">only={["xs", "sm", "lg", "xl"]}</code>.<br>
The error message is:<br>
<code class="notranslate">string.charAt is not a function. (In 'string.charAt(0)', 'string.charAt' is undefined)</code></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/mui-org/material-ui/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">It should compile and work</p>
<h2 dir="auto">Current Behavior</h2>
<p dir="auto">doesn't compile</p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>
<p dir="auto"><a href="https://codesandbox.io/s/1okvkyj7xj" rel="nofollow">https://codesandbox.io/s/1okvkyj7xj</a></p>
<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>Material-UI</td>
<td>next</td>
</tr>
<tr>
<td>React</td>
<td>latest</td>
</tr>
<tr>
<td>browser</td>
<td>any</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/callemall/material-ui/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">When having Menu items display conditionally it should work as expected.</p>
<h2 dir="auto">Current Behavior</h2>

<p dir="auto">When condition evaluates to false and MenuItem is not rendered an error pops up: <code class="notranslate">Cannot read property 'props' of null</code></p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>

<p dir="auto"><a href="https://codesandbox.io/s/24mlj7qzjr" rel="nofollow">https://codesandbox.io/s/24mlj7qzjr</a></p>
<ol dir="auto">
<li>Add a condition to display a MenuItem:</li>
</ol>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="{allowEmpty &amp;&amp; (
                &lt;MenuItem value=&quot;&quot;&gt;
                  &lt;em&gt;None&lt;/em&gt;
                &lt;/MenuItem&gt;
              )}"><pre class="notranslate"><code class="notranslate">{allowEmpty &amp;&amp; (
                &lt;MenuItem value=""&gt;
                  &lt;em&gt;None&lt;/em&gt;
                &lt;/MenuItem&gt;
              )}
</code></pre></div>
<ol start="2" dir="auto">
<li>Evaluate condition to false.</li>
</ol>
<h2 dir="auto">Context</h2>
    
<p dir="auto">I want to controll rendering of empty MenuItem with flag allowEmpty.<br>
The problem occurs from this loop where child is not checked for undefined or null and tries to access child props.<br>
<a href="https://github.com/callemall/material-ui/blob/v1-beta/src/Select/SelectInput.js#L278">https://github.com/callemall/material-ui/blob/v1-beta/src/Select/SelectInput.js#L278</a><br>
<a href="https://github.com/callemall/material-ui/blob/v1-beta/src/Select/SelectInput.js#L283">https://github.com/callemall/material-ui/blob/v1-beta/src/Select/SelectInput.js#L283</a></p>
<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>Material-UI</td>
<td>1.0.0-beta.9</td>
</tr>
<tr>
<td>React</td>
<td>15.5.3</td>
</tr>
<tr>
<td>browser</td>
<td>Chrome Version 60.0.3112.113 (Official Build) (64-bit)</td>
</tr>
<tr>
<td>etc</td>
<td></td>
</tr>
</tbody>
</table>