title: php json_decode returning infinite
body: <p>If I run the following, no error is returned and the value of $result is <code>INF</code>. <code>json_last_error()</code> returns <code>0</code>.</p>
  
  <p><code>$result = json_decode('547533e683433', true);</code></p>
  
  <p>As this is a string and not JSON I would expect <code>$result</code> to be <code>NULL</code> and <code>json_last_error()</code> to return <code>4</code> or <code>JSON_ERROR_SYNTAX</code>.</p>
  
  <p>Why is this happening?</p>