title: date-fns format(fromUnixTime(1584161862798), 'yyyyMMdd') invalid time value
body: <p>I am using date-funs library to manage dates. 
  ( version 2.12.0 )
  I need to format unix datetime to 'yyyyMMdd'.
  And I am getting 'invalid time value' error.</p>
  
  <pre><code>fromUnixTime(1584161862798) 
  // Sat Feb 03 52170 22:13:34 GMT+0900 (대한민국 표준시)
  
  format(startDate, 'yyyyMMdd');
  // invalid time value
  </code></pre>
  
  <p>I am nor sure why this is not working, when </p>
  
  <pre><code>format(new Date(), 'yyyyMMdd')
  // 20200413
  </code></pre>
  
  <p>this works.</p>
  
  <p>I tried to parse the date. It still returns the same error.</p>
  
  <pre><code>format(parseISO(startDate), 'yyyyMMdd');
  // invalid time value
  </code></pre>
  
  <p>Thanks in advance.</p>