<p dir="auto">&lt;Button disableRipple /&gt; throws an exception when the KeyDown event triggered.</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">Pressing the spacebar over keyboardFocused button should`t lead to exception.</p>
<h2 dir="auto">Current Behavior</h2>
<p dir="auto"><a href="https://github.com/mui-org/material-ui/blob/c17d66e187cbb9acdd86c0c3735c84735085e836/src/ButtonBase/ButtonBase.js#L113">https://github.com/mui-org/material-ui/blob/c17d66e187cbb9acdd86c0c3735c84735085e836/src/ButtonBase/ButtonBase.js#L113</a><br>
This line does not protect from that the this.ripple can be null.</p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>
<p dir="auto"><a href="https://codesandbox.io/s/z6jwnmzq1p" rel="nofollow">https://codesandbox.io/s/z6jwnmzq1p</a></p>
<ol dir="auto">
<li>Focus the button by keyboard</li>
<li>Press the spacebar</li>
</ol>
<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">As I use material components, they mostly come with the Robot font and I've found that Subheader is the first one I encountered that doesn't have the font declared. I was expecting it to be styled since other components are.</p>
<h2 dir="auto">Current Behavior</h2>

<p dir="auto">The Subheader is not styled with a font family.</p>