WIP: Use failure
This is WIP because I'm not sure which commit should be used. Internal fine-grained error kinds or globbing them together (the kinds aren't exposed here anyways since there's not much callers can do based on the error that happened anyways).
An alternative would be to have a different Error
type for each call (e.g., PrepareError
, ReserveError
, etc.).
Builds on top of !62 (merged).