add a check to make sure we don't try to select a teachpack when the user clicks on empty space
add a check to make sure we don't try to select a teachpack when the
user clicks on empty space

closes PR 12472

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket