refactor: reduce repeated code in state machine

This replaces repeated boilerplate code around handling taking/putting
the state with a wrapper type. This wrapper type moves the state machine
itself into a closure, allowing nice things like using ? to return
errors and other early returns. It also makes simple an "Errored" state
for the state machine so that calling the state machine after it's
already returned an error is no longer a panic.

Signed-off-by: Nick Stevens <[email protected]>