YMQ Connectors log "terminate called without active exception"

After the integration of YMQ for Scaler, one might see log message like this when running test cases:
```
terminate called without active exception
....
```

Notice that unlike usual cause of this message, this one doesn't have any `Aborted(Core dumped)` message. Nor is it a thread destruction problem.

But it doesn't seem to affect the correctness.