{% apibody %} r.error(message) → error {% endapibody %}

Throw a runtime error. If called with no arguments inside the second argument to default, re-throw the current error.

Example: Iron Man can't possibly have lost a battle:

r.table('marvel').get('IronMan').do(function(ironman) {
    return r.branch(ironman('victories').lt(ironman('battles')),
        r.error('impossible code path'),
        ironman)
}).run(conn, callback)