error:
       … while evaluating a path segment
         at /pwd/lang/eval-fail-bad-string-interpolation-1.nix:1:2:
            1| "${x: x}"
             |  ^
            2|

       error: cannot coerce a function to a string: «lambda @ /pwd/lang/eval-fail-bad-string-interpolation-1.nix:1:4»
