All error conditions should goes into the callback for Iterator.
All error conditions should goes into the callback for Iterator.

watson/abstract-leveldown,calvinmetcalf/SQLdown,ralphtheninja/abstract-leveldown,ralphtheninja/abstract-leveldown,calvinmetcalf/SQLdown,bigeasy/abstract-leveldown,bryce-gibson/SQLdown,snowyu/node-abstract-nosql,bryce-gibson/SQLdown,shimonenator/couchbasedown,Level/abstract-leveldown