added amqp error

client.go

@@ -14,10 +14,12 @@ var (
 	errNotConnected  = errors.New("not connected to a server")
 	errAlreadyClosed = errors.New("already closed: not connected to the server")
 	errShutdown      = errors.New("client is shutting down")
-
-	AmqpError = amqp.Error{}
 )
 
+func AmqpError() amqp.Error {
+	return amqp.Error{}
+}
+
 const (
 	DeliveryModeTransient  = amqp.Transient
 	DeliveryModePersistent = amqp.Persistent