No harm in playing both, IME, and I'm pushing four decades of doing so. While I was always mainly a bass player, I was never without a couple of guitars either. Guitar helped me explore harmony-related spaces that bass didn't offer, and vice versa.
Obviously, YMMV and then some.
This is exactly my experience. I started on guitar at age 7 and added upright bass in fourth grade (elementary school orchestra). I switched primarily to bass when my guitar teacher (who was a gigging bassist) suggested that guitarists were "a dime a dozen" and I'd have more fun as a bassist. He was right but I still play guitar now and then. It definitely helps my bass playing, especially being able to pick out chords the guitarists are playing.
