message: Fix bad_function_call exception
diff: @@ -192,10 +192,9 @@ public:
  g(err);
  }
  };
  - auto wrapped_helper = helper.wrap();
  for (auto id : ids_) {
  typename Self::accept_one_cond rc;
  - self->varargs_receive(rc, id, wrapped_helper, error_handler);
  + self->varargs_receive(rc, id, helper.wrap(), error_handler);
  }
  }
  