Errors

Defer is for use when defering a function call that can return an error.

Execute is intended to be used as the top level function call of a CLI.

Merge is a convenience method for making a Slice of errors and calling the Merge method.

Multierr wraps multiple errors.

ExitCoder is an optional interface that errors can implement to change what exit code they cause Execute to return.

Slice is a slice of errors that implements the error interface itself.