error:
       … writing file "/nix/store/4f4f96dvz5w2lcn0czbc2sh76bvs4291-ldexpl.c"

       error: unable to download 'https://gitlab.com/janneke/mes/-/raw/c837abed8edb341d4e56913729fbe9803b4de47c/lib/math/ldexpl.c': HTTP error 404