Today I've discovered a couple of errors in the logs related to #eventbus, which I could narrow down to 2 issues with test cases:
Problem 1:
If the field is optional, but it's value is specified as `null`, eventlogging-service rejects the event with `None is not of type 'string'` message.
Example:
```
curl -XPOST -H 'content-type: application/json' localhost:8085/v1/events --data '{"user_blocked": "201.10.143.37", "reason": null, "meta": {"domain": "pt.wikipedia.org", "uri": "/user_block/uri", "topic": "mediawiki.user_block", "request_id": "9b0ff34e-402c-421b-8bb1-840462cdae0b", "schema_uri": "user_block/1", "dt": "2016-05-14T16:42:02+00:00", "id": "c8b10681-19f2-11e6-aab2-90b11c2793de"}, "user_id": 1053698, "user_text": "\u00d6nni", "blocks": {"account_create": true, "user_talk": false, "name": false, "email": false}, "expiry": "20160514174202"}'
```
Note the `"reason": null` part, it's the core of the problem.
Problem 2.
If I fix up the previous issue by providing a value to the service, it successfully emits an event, but for some reason responds with 500 and `<html><title>500: Internal Server Error</title><body>500: Internal Server Error</body></html>` message. I'm using the service from vagrant installation.
Example:
```
curl -i -XPOST -H 'content-type: application/json' localhost:8085/v1/events --data '{"user_blocked": "201.10.143.37", "meta": {"domain": "pt.wikipedia.org", "uri": "/user_block/uri", "topic": "mediawiki.user_block", "request_id": "9b0ff34e-402c-421b-8bb1-840462cdae0b", "schema_uri": "user_block/1", "dt": "2016-05-14T16:42:02+00:00", "id": "c8b10681-19f2-11e6-aab2-90b11c2793de"}, "user_id": 1053698, "user_text": "\u00d6nni", "blocks": {"account_create": true, "user_talk": false, "name": false, "email": false}, "expiry": "20160514174202"}'
```