Slim Application Error

The application could not run because of the following error:

Details

Type: Error
Message: Function name must be a string
File: /var/www/rl2020.vitronic.com/app/model/extensions/Icon__proceed.php
Line: 34

Trace

#0 /var/www/rl2020.vitronic.com/app/model/extensions/NavigationLink.php(35): Icon__proceed->render()
#1 /var/www/rl2020.vitronic.com/app/model/extensions/TeaserCard.php(474): NavigationLink->render()
#2 /var/www/rl2020.vitronic.com/app/model/extensions/TeaserCardGroup__large_text_only.php(36): TeaserCard->render()
#3 /var/www/rl2020.vitronic.com/app/model/extensions/CorporateContent.php(277): TeaserCardGroup__large_text_only->render()
#4 /var/www/rl2020.vitronic.com/app/views/corporate-content.php(30): CorporateContent->render()
#5 /var/www/rl2020.vitronic.com/app/includes/http.php(16): require('/var/www/rl2020...')
#6 /var/www/rl2020.vitronic.com/app/app.php(299): render()
#7 [internal function]: Closure->{closure}()
#8 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/Handlers/Strategies/RequestResponse.php(40): call_user_func()
#9 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/Route.php(281): Slim\Handlers\Strategies\RequestResponse->__invoke()
#10 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(117): Slim\Route->__invoke()
#11 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/Route.php(268): Slim\Route->callMiddlewareStack()
#12 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/App.php(503): Slim\Route->run()
#13 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/MiddlewareAwareTrait.php(117): Slim\App->__invoke()
#14 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/App.php(392): Slim\App->callMiddlewareStack()
#15 /var/www/rl2020.vitronic.com/vendor/slim/slim/Slim/App.php(297): Slim\App->process()
#16 /var/www/rl2020.vitronic.com/public/index.php(103): Slim\App->run()
#17 {main}
VITRONIC implementation services