Infinite recursion encountered

I’ve been using Nix with home-manager on Ubuntu since almost 2 months. I’m pretty satisfied with my home configuration, mostly based on stuff copied and modified from others. However, I am unable to run nix-shell or nix-env, because I’m getting

❯ nix-shell -p nix-info --run "nix-info -m"
error: infinite recursion encountered

       at /nix/store/9lkm36ac7hfl7f9h2z9dj00mdh30mjhi-source/lib/fixed-points.nix:69:67:

           68|   #
           69|   extends = f: rattrs: self: let super = rattrs self; in super // f self super;
             |                                                                   ^

I found a few threads about similar problems, removed all occurrences of rec, but that didn’t help. What’s the best way to track down the culprit? Running commands with --show-trace outputs a long trace.
My dot-files: GitHub - kciesielski/dot-files
Trace output: