propogate err to condRelease in withAddrRw

[jlisthood]

Currently, withAddrRw always calls defer cn.condRelease(&err) with an err that is nil. This means no matter what error happens in fn, the connection will get sent back to the pool even if there is a non-resumable error. This isn't ideal because we could be sending bad connections back to the pool.

This PR matches the implementation with onItem that seems to handle the error correctly.