Proper HTTP error codes on errors

[peterbe]

Let errors happen and when they do the server should yield correct 5xx error codes.

[peterbe]

Maybe once the errors work we can introduce raven (Sentry).

[willkg]

I'm not entirely sure I understand this. Are you suggesting that if one of the tasks fails, then the HTTP response should be an HTTP 500 with none of the data from successful tasks?