title: TypeError: unsupported format string passed to NoneType.__format__ with f-string in Python
body: <p>I noticed something strange when formatting my variable into a consistent width of 11 characters:</p>
  <pre class="lang-py prettyprint-override"><code>&gt;&gt;&gt; a = 1234
  &gt;&gt;&gt; b = None
  
  &gt;&gt;&gt; f'{a}'
  '1234'
  &gt;&gt;&gt; f'{b}'
  'None'
  
  &gt;&gt;&gt; f'{a:&gt;11}'
  '       1234'
  &gt;&gt;&gt; f'{b:&gt;11}'
  Traceback (most recent call last):
    File &quot;&lt;stdin&gt;&quot;, line 1, in &lt;module&gt;
  TypeError: unsupported format string passed to NoneType.__format__
  </code></pre>