Errors are part of our daily lives as Ruby developers. We first encounter them in our development environments where they materialize from a misplaced comma, an eagerly-typed bracket, or a misunderstood method call. We fix them and move on, dismissing them as creatures of our own creation. Sometimes the cause is deeper--not readily apparent. We learn to debug. We learn to rescue. We set traps for our insubordinate creature creations. We write tests to make sure our code is creature-free. When we...