error:
       … while evaluating the attribute 'relativePath'
         at /pwd/lang/eval-fail-readDir-nonexistent-2.nix:2:3:
            1| {
            2|   relativePath = builtins.readDir ./this/path/really/should/not/exist;
             |   ^
            3| }

       … while calling the 'readDir' builtin
         at /pwd/lang/eval-fail-readDir-nonexistent-2.nix:2:18:
            1| {
            2|   relativePath = builtins.readDir ./this/path/really/should/not/exist;
             |                  ^
            3| }

       error: path '/pwd/lang/this/path/really/should/not/exist' does not exist