lib.customisation: Don't allocate intermediate list for missing args

      # a list of argument names that the function requires, but

      # wouldn't be passed to it

      missingArgs = attrNames

      missingArgs =

        # Filter out arguments that have a default value

        (filterAttrs (name: value: ! value)

        # Filter out arguments that would be passed

        + "${loc'}${prettySuggestions (getSuggestions arg)}";

      # Only show the error for the first missing argument

      error = errorForArg (head missingArgs);

      error = errorForArg missingArgs.${head (attrNames missingArgs)};

    in if missingArgs == [] then makeOverridable f allArgs else abort error;

    in if missingArgs == {} then makeOverridable f allArgs else abort error;

  /* Like callPackage, but for a function that returns an attribute