"XXXX can't be processed. The connection is already closed."

[blackmad]

I've noticed a bunch of these errors, would it be helpful if all the handy-redis wrappers checked .nodeClient.connected before attempting commands?

cf redis/node-redis#1157

[mmkal]

What would you suggest this library do here? In general, I would prefer to keep this is as a thin wrapper but if you can propose something specific that doesn't add a lot of responsibility to this package, I'd consider it.