error:
       … from call site
         at /pwd/lang/eval-fail-missing-arg.nix:1:1:
            1| (
             | ^
            2|   {

       error: function 'anonymous lambda' called without required argument 'y'
       at /pwd/lang/eval-fail-missing-arg.nix:2:3:
            1| (
            2|   {
             |   ^
            3|     x,