Client.Call(): do not return error if no Status is set (gRPC v1.23 an…

…d up)

To account for grpc/grpc-go@5da5b1f,
which is part of gRPC v1.23.0 and up, and after which gRPC no longer sets a
Status if no error occured.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client.go

@@ -134,11 +134,11 @@ func (c *Client) Call(ctx context.Context, service, method string, req, resp int
 		return err
 	}
 
-	if cresp.Status == nil {
-		return errors.New("no status provided on response")
+	if cresp.Status != nil {
+		return status.ErrorProto(cresp.Status)
 	}
 
-	return status.ErrorProto(cresp.Status)
+	return nil
 }
 
 func (c *Client) dispatch(ctx context.Context, req *Request, resp *Response) error {