Fatal error: Uncaught Error: Call to undefined function App\add_action() in /home/k1799/dev.studiohamerhaai.nl/wp-content/themes/hamerhaai/app/admin.php:8 Stack trace: #0 {main} thrown in /home/k1799/dev.studiohamerhaai.nl/wp-content/themes/hamerhaai/app/admin.php on line 8