Bug of `format_ae_listing` -- SEX, RACE, AGE

[LittleBeannie]

https://github.com/Merck/forestly/blob/main/R/ae_listing.R#L211-L215
These lines of code requires SEX, RACE, AGE is must included in AE listing. If users didn't select them, then they will get errors.

Debuging example can be found at #123