fix crash on VM cloning

vsphere-influxdb.go

@@ -449,8 +449,10 @@ func (vcenter *VCenter) Query(config Configuration, InfluxDBClient influxclient.
 		if vmToPool[vm.Self] != "" {
 			vmSummary[vm.Self]["respool"] = vmToPool[vm.Self]
 		}
+		if vm.Summary.Runtime.Host != nil {
 			vmSummary[vm.Self]["esx"] = hostSummary[*vm.Summary.Runtime.Host]["name"]
 		}
+	}
 
 	// get object names
 	objects := []mo.ManagedEntity{}