Summary:
At the moment, we can see the %-success of instrumented operations, but it's hard to attribute the ones that fail to actual errors.
This will allow us to see for every session-event row, the error messages that caused each of the failures.
Then if necessary, you can search for that error message in logview to get more info like the stack trace.
Requires a corresponding change in puma, since this is changing a number to a json value.
Reviewed By: danielbuechele
Differential Revision: D15099185
fbshipit-source-id: b966e6e55ab82f1cb9a4cfd7bf02034a1df01929