I get undefined function pager_navigation from time to time, although I have in the file use_helper('Global'); and in lib/helper/GlobalHelper.php there is function pager_navigation.
Deleting cache does not help. Only putting ?> at the end of the GlobalHelper.php solves the issue. Then after a while I get this error again, and removing ?> at the end of GlobalHelper.php solves the issue.
Any ideas how to solve the issue permanently and what is the cause of it?