Validator nil duty should not panic (#8171)

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

validator/client/log.go

@@ -43,6 +43,9 @@ func (v *validator) LogNextDutyTimeLeft(slot uint64) error {
 	if !v.logDutyCountDown {
 		return nil
 	}
+	if v.duties == nil {
+		return nil
+	}
 
 	var nextDutySlot uint64
 	var role string

validator/client/log_test.go

@@ -49,3 +49,10 @@ func TestLogNextDutyCountDown_HasDutyProposer(t *testing.T) {
 	require.NoError(t, v.LogNextDutyTimeLeft(101))
 	require.LogsContain(t, hook, "\"Next duty\" currentSlot=101 dutySlot=105 prefix=validator role=proposer")
 }
+
+func TestLogNextDutyCountDown_NilDuty(t *testing.T) {
+	v := &validator{
+		logDutyCountDown: true,
+	}
+	require.NoError(t, v.LogNextDutyTimeLeft(101))
+}