Add error message to DOCA functor
DOCA functor currently causes a segmentation fault of the Gaudí application when a child index specified is greater than the total number of children. With this fix it would throw a FATAL and stop the application.
DOCA functor currently causes a segmentation fault of the Gaudí application when a child index specified is greater than the total number of children. With this fix it would throw a FATAL and stop the application.