{{flash.output()}} undefined when Volt set to 'always' => false, 'stat' => false

When Volt is set to 'always' => false, 'stat' => false, the compiled templates will show "flash" or "flashSession" undefined errors.

The solution I found is to use <?= $this->flashSession->output ?>.

In fact, I'm not sure if other volt functions suffer from the same issue because I usually just type php, which is usually shorter anyway.