error:
       … in the condition of the assert statement
         at /pwd/lang/eval-fail-print-limit-set.nix:1:1:
            1| assert (
             | ^
            2|   let x = { a.a.a.a.a.a.a.a.a = { a.a = 1; b = 2; }; a.b.c.x = 3; c = 4; };

       error: expected a Boolean but found a set: { a = { a = { a = { a = { a = { a = { a = { a = { a = { a = { ... }; b = 2; }; }; }; }; }; }; }; }; «1 attribute elided» }; «1 attribute elided» }
       at /pwd/lang/eval-fail-print-limit-set.nix:1:1:
            1| assert (
             | ^
            2|   let x = { a.a.a.a.a.a.a.a.a = { a.a = 1; b = 2; }; a.b.c.x = 3; c = 4; };