message: fix warning in release mode
diff: @@ -28,8 +28,7 @@ State::State(const Function &f) : f(f) {
  const StateValue& State::exec(const Value &v) {
  assert(undef_vars.empty());
  auto val = v.toSMT(*this);
  - auto p = values_map.try_emplace(&v, (unsigned)values.size());
  - assert(p.second);
  + ENSURE(values_map.try_emplace(&v, (unsigned)values.size()).second);
  values.emplace_back(&v, ValTy(move(val), move(undef_vars)));
  // cleanup potentially used temporary values due to undef rewriting
  