On a read error, show the node number the error came from

App/teems.cpp

@@ -259,8 +259,8 @@ int main(int argc, char **argv)
             NodeIO &node = netio.node(node_num);
             node.recv_commands(
                 // error_cb
-                [](boost::system::error_code ec) {
-                    printf("Error %s\n", ec.message().c_str());
+                [node_num](boost::system::error_code ec) {
+                    printf("Error %s from %d\n", ec.message().c_str(), node_num);
                 },
                 // epoch_cb
                 [](uint32_t epoch) {