fix panic when monitor starts too quickly (#260)

Author: frostbyte73

pkg/stats/monitor.go

@@ -86,7 +86,9 @@ func NewMonitor(conf *config.Config) (*Monitor, error) {
 		maxUtilization: conf.MaxCpuUtilization,
 	}
 	cpu, err := hwstats.NewCPUStats(func(idle float64) {
-		m.cpuLoad.Set(1 - idle/m.cpu.NumCPU())
+		if m.cpu != nil {
+			m.cpuLoad.Set(1 - idle/m.cpu.NumCPU())
+		}
 	})
 	if err != nil {
 		return nil, err