Service crash handling

A few little improvements. ;)

---

Currently https://counterwallet.co/_t_api is saying:

```json
{"counterpartyd": "NOT OK", "counterblockd_ver": "1.4.0", "counterpartyd_ver": "?", "counterblockd": "OK", "counterblockd_check_elapsed": 0.0035178661346435547, "counterpartyd_last_block": "?", "local_online_users": 0, "counterpartyd_check_elapsed": 0.0005960464477539062, "counterblockd_error": null, "counterpartyd_last_message_index": "?"}
```

It makes the library crash before it gets to the point where the balances are listed to the user. Sad. But hey! this pull request fixes it!