Use throwing functions instead of returning a boolean

[jksk]

We're seeing a small amount of unreproducible failures in production. If something goes wrong, the boolean return value doesn't tell you why. A throwing function contains more information that can be used for debugging.

[jrendel]

@jksk Sorry I have no been maintaining this. I just went through and merged a bunch of PRs. If you want to update the conflicts now I can merge this in.

[jksk]

I updated the PR.