06a5edf247
It assumes the parent is a vector or scalar so we need to fail if it
isn't.
Fixes: 9190f82d57 "nir/opt_deref: Add an optimization for bitcasts"
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7064>