Fatal error: Uncaught exception Error with message Function name must be a string thrown in system/modules/core/classes/FrontendTemplate.php on line 45

#0 system/modules/core/modules/Module.php(165): Contao\FrontendTemplate->parse()
#1 system/modules/core/library/Contao/Controller.php(300): Contao\Module->generate()
#2 system/modules/core/pages/PageRegular.php(109): Contao\Controller->getFrontendModule(Object(Contao\ModuleModel), 'header')
#3 index.php(250): Contao\PageRegular->generate(Object(Contao\PageModel))
#4 index.php(411): Index->run()
#5 {main}