fix(ios): propagate error from BootedUDID instead of silently swallowing

internal/ios/ios.go

@@ -55,12 +55,15 @@ func EnsureSimulator(ctx context.Context, deviceName string, stdout io.Writer) e
 }
 
 // BootedUDID returns the UDID of the currently booted iOS simulator, or "" if none is booted.
-func BootedUDID(ctx context.Context) string {
-	d, _ := bootedSimulator(ctx)
-	if d == nil {
-		return ""
+func BootedUDID(ctx context.Context) (string, error) {
+	d, err := bootedSimulator(ctx)
+	if err != nil {
+		return "", err
 	}
-	return d.UDID
+	if d == nil {
+		return "", nil
+	}
+	return d.UDID, nil
 }
 
 func bootedSimulator(ctx context.Context) (*simDevice, error) {

internal/ios/ios_test.go

@@ -82,7 +82,10 @@ func TestPickSimulator_EmptyList(t *testing.T) {
 func TestBootedUDID_CanceledContext(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
-	udid := BootedUDID(ctx)
+	udid, err := BootedUDID(ctx)
+	if err == nil {
+		t.Error("expected error for canceled context, got nil")
+	}
 	if udid != "" {
 		t.Errorf("expected empty UDID on canceled context, got %q", udid)
 	}