Thats really strange, i can add this:
<?php snippet('s_about', ['page' => page('about')], false) ?>to every template but not in the about template.
I thought it’s cause of the name, so i renamed the snippet to s_about. Now i am getting another error:
kirby\kirby\component\template.php
array_merge(): Argument #2 is not an array
But again, it works in every other template.