message: fix crash with reachable but unreachable BBs
diff: @@ -575,6 +575,7 @@ bool State::startBB(const BasicBlock &bb) {
  analysis.meet_with(data.analysis);
  isFirst = false;
  }
  + assert(!isFirst);
  domain.path = path();
  domain.UB = *UB();
  @@ -585,6 +586,7 @@ bool State::startBB(const BasicBlock &bb) {
  }
  void State::addJump(const BasicBlock &dst0, expr &&cond) {
  + cond &= domain.path;
  if (cond.isFalse())
  return;
  @@ -593,7 +595,6 @@ void State::addJump(const BasicBlock &dst0, expr &&cond) {
  dst = &f.getSinkBB();
  }
  - cond &= domain.path;
  auto &data = predecessor_data[dst][current_bb];
  data.mem.add(memory, cond);
  data.UB.add(domain.UB(), cond);
  