error:
       … while evaluating a path segment
         at /pwd/lang/eval-fail-bad-string-interpolation-4.nix:9:3:
            8| # The error message should not be too long.
            9| ''${pkgs}''
             |   ^
           10|

       error: cannot coerce a set to a string: { a = { a = { a = { a = "ha"; b = "ha"; c = "ha"; d = "ha"; e = "ha"; f = "ha"; g = "ha"; h = "ha"; j = "ha"; }; «8 attributes elided» }; «8 attributes elided» }; «8 attributes elided» }