cmd/update: tweak error message.
cmd/update: tweak error message.

Co-authored-by: Bo Anderson <1d6e1cf70ec6f9ab28d3ea4b27a49a77654d370e@boanderson.me>
MikeMcQuaid/brew,nandub/brew,MikeMcQuaid/brew,MikeMcQuaid/brew,Homebrew/brew,Homebrew/brew,nandub/brew,nandub/brew,Homebrew/brew,MikeMcQuaid/brew,Homebrew/brew,nandub/brew