fix: stop iqr filtering on empty list

cmd/icmperf/main.go

@@ -30,7 +30,8 @@ func main() {
 		return nil
 	})
 
-	m := model.NewModel(pinger, record, (*net.UDPAddr)(&cli.Target), cli.MTU, cli.Duration)
+	peer := net.UDPAddr(cli.Target)
+	m := model.NewModel(pinger, record, &peer, cli.MTU, cli.Duration)
 	if err := pinger.Start(ctx); err != nil {
 		ktx.FatalIfErrorf(err)
 	}

pkg/cli/cli.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"fmt"
 	"net"
 	"time"
 )
@@ -10,7 +11,7 @@ type Target net.UDPAddr
 func (t *Target) UnmarshalText(text []byte) error {
 	ip, err := net.LookupIP(string(text))
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to lookup target: %w", err)
 	}
 	t.IP = ip[0]
 	return nil

pkg/recorder/stats.go

@@ -20,6 +20,11 @@ type Stats struct {
 // iqrFilter filters the data using the Interquartile Range method.
 func iqrFilter(data []float64) []float64 {
 	sort.Float64s(data)
+	if len(data) < 4 {
+		// Not enough data to filter
+		return data
+	}
+
 	q1 := data[len(data)/4]
 	q3 := data[3*len(data)/4]
 	iqr := q3 - q1