[BUGFIX] Empty __call() function hides implementation errors

Throw an Exception if this method hits.

Change-Id: Ide94043bb008e1dfaf19b452570ce70d5f2aa432
Resolves: #51924
Releases: 6.2, 6.1
Reviewed-on: https://review.typo3.org/23763
Reviewed-by: Ernesto Baschny
Tested-by: Ernesto Baschny
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel