Steps to reproduce the issue

I had this error:

PHP Fatal error: Call to a member function format() on null in /www/joomla/sede/plugins/quickicon/phpversioncheck/phpversioncheck.php on line 174

I use Joomla 3.8.1 on PHP 5.6

The problem is a simple null pointer. The array of supported PHP versions is fixed. Yesterday 2019/12/1, the last PHP version on the array, lost support https://github.com/joomla/joomla-cms/blob/3.8.1/plugins/quickicon/phpversioncheck/phpversioncheck.php#L130

Because of this, recommendedVersionEndOfSupport is null, and can´t be called format on

I understand that Joomla 3.8.1 is not the last version, and PHP 5.6 is unsupported, but this is beyond the point. I understand that a updated environment and version is the way to go, but this is a bug that breaks access from one day to the other without user intervention.

Expected result

Maybe show something like "Update Joomla to show the recommended PHP version"

Actual result

White page on the administrator page

System information (as much as possible)

PHP 5.6
Joomal 3.8.1