impossible happened: initTc: unsolved constraints

Below is the error:

I got the following error:

ghc: panic! (the 'impossible' happened)
      (GHC version 8.0.1.20161213 for x86_64-unknown-linux):
        initTc: unsolved constraints
      WC {wc_insol =
            [W] cp_a6SB :: t_a6SA[tau:1] (CHoleCan: cp)
            [W] minimal_a6SI :: t_a6SH[tau:1] (CHoleCan: minimal)
            [W] frames_a6SL :: t_a6SK[tau:1] (CHoleCan: frames)
            [W] ps_a6Tb :: t_a6Ta[tau:1] (CHoleCan: ps)
            [W] minimal_a6Ti :: t_a6Th[tau:1] (CHoleCan: minimal)
            [W] frames_a6Tm :: t_a6Tl[tau:1] (CHoleCan: frames)
            [W] map_hd_a6Tv :: t_a6Tu[tau:1] (CHoleCan: map_hd)
            [W] ps_a6Ty :: t_a6Tx[tau:1] (CHoleCan: ps)}

It was created with this repo: https://github.com/codygman/minimal-frames-lookup-map/blob/master/src/Main.hs

Apologies for the setup needed, but I also had to download judy-0.3.0 manually and then include it for it to build (not sure why, but unrelated problem I think).

GHC Head is still compiling for me, but maybe I'll be able to try to reproduce this with HEAD tomorrow.