When I was installing gentoo on a new machine, atfer emerge system I've do emerge gnome, but the emerging process stopped in aspell-en and there where some lines where says "which: commnand not found". After that I've emerged sys-apps/which and it works like a charm. So please add sys-apps/which as a aspell dictionaries dependencies. Reproducible: Always Steps to Reproduce: 1. 2. 3.
the aspell-dict eclass is fixed now