fix(commands): handle nil list responses safely

internal/commands/checkouts/checkouts.go

@@ -162,8 +162,9 @@ func listCheckouts(ctx context.Context, cmd *cli.Command) error {
 		return display.PrintJSON(appCtx.Output, checkoutList)
 	}
 
-	rows := make([][]attribute.Value, 0, len(*checkoutList))
-	for _, checkout := range *checkoutList {
+	checkouts := util.SliceOrEmpty(checkoutList)
+	rows := make([][]attribute.Value, 0, len(checkouts))
+	for _, checkout := range checkouts {
 		status := "-"
 		if checkout.Status != nil {
 			status = string(*checkout.Status)

internal/commands/customers/customers.go

@@ -222,8 +222,9 @@ func listPaymentInstruments(ctx context.Context, cmd *cli.Command) error {
 		return display.PrintJSON(appCtx.Output, instruments)
 	}
 
-	rows := make([][]attribute.Value, 0, len(*instruments))
-	for _, instrument := range *instruments {
+	paymentInstruments := util.SliceOrEmpty(instruments)
+	rows := make([][]attribute.Value, 0, len(paymentInstruments))
+	for _, instrument := range paymentInstruments {
 		rows = append(rows, []attribute.Value{
 			attribute.OptionalStringValue(instrument.Token),
 			attribute.OptionalValue(instrument.Type),

internal/commands/payouts/payouts.go

@@ -12,6 +12,7 @@ import (
 	"github.com/sumup/sumup-go/datetime"
 
 	"github.com/sumup/sumup-cli/internal/app"
+	"github.com/sumup/sumup-cli/internal/commands/util"
 	"github.com/sumup/sumup-cli/internal/display"
 	"github.com/sumup/sumup-cli/internal/display/attribute"
 )
@@ -97,8 +98,9 @@ func listPayouts(ctx context.Context, cmd *cli.Command) error {
 		return display.PrintJSON(appCtx.Output, payoutList)
 	}
 
-	rows := make([][]attribute.Value, 0, len(*payoutList))
-	for _, payout := range *payoutList {
+	payouts := util.SliceOrEmpty(payoutList)
+	rows := make([][]attribute.Value, 0, len(payouts))
+	for _, payout := range payouts {
 		fee := attribute.OptionalValue(payout.Fee)
 		if payout.Fee != nil {
 			fee = attribute.ValueOf(fmt.Sprintf("%.2f", *payout.Fee))

internal/commands/util/util.go

@@ -58,3 +58,10 @@ func BoolLabel(value *bool) string {
 	}
 	return "No"
 }
+
+func SliceOrEmpty[S ~[]E, E any](value *S) S {
+	if value == nil {
+		return S{}
+	}
+	return *value
+}

internal/commands/util/util_test.go

@@ -83,6 +83,20 @@ func TestBoolLabel(t *testing.T) {
 	})
 }
 
+func TestSliceOrEmpty(t *testing.T) {
+	t.Parallel()
+
+	t.Run("returns empty slice for nil pointer", func(t *testing.T) {
+		var values *[]string
+		assert.Empty(t, util.SliceOrEmpty(values))
+	})
+
+	t.Run("returns dereferenced slice when present", func(t *testing.T) {
+		values := []string{"a", "b"}
+		assert.Equal(t, values, util.SliceOrEmpty(&values))
+	})
+}
+
 func TestTimeOrDash(t *testing.T) {
 	t.Parallel()