Something went wrong :(

Exception: 'Error' with message
Undefined constant "IS_SUBPAGE"
Stack trace:
#0 /home/touchfi1/domains/touchfitpraktijk.nl/public_html/framework/application/frontend/page/controller.php(48): NewsoverviewBlockController->show()
#1 /home/touchfi1/domains/touchfitpraktijk.nl/public_html/framework/tmp/e7bf6a5e69eaf70255a06b8b699f13ad.tmp(46): PageFrontController->parseArea()
#2 /home/touchfi1/domains/touchfitpraktijk.nl/public_html/index.php(883): include('...')
#3 {main}
thrown in /home/touchfi1/domains/touchfitpraktijk.nl/public_html/framework/application/blocks/newsoverview/controller.php on line 36