avoid panic when result has only 0 or 1 line
avoid panic when result has only 0 or 1 line

mackerelio/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,mackerelio/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,xorphitus/mackerel-agent-plugins,hiroakis/mackerel-agent-plugins