Ensure aggregateAndProofSig returns when err'ing (#7182)

* Return if sign fails

validator/client/aggregate.go

@@ -78,6 +78,7 @@ func (v *validator) SubmitAggregateAndProof(ctx context.Context, slot uint64, pu
 	sig, err := v.aggregateAndProofSig(ctx, pubKey, res.AggregateAndProof)
 	if err != nil {
 		log.Errorf("Could not sign aggregate and proof: %v", err)
+		return
 	}
 	_, err = v.validatorClient.SubmitSignedAggregateSelectionProof(ctx, &ethpb.SignedAggregateSubmitRequest{
 		SignedAggregateAndProof: &ethpb.SignedAggregateAttestationAndProof{

validator/client/aggregate_test.go

@@ -2,6 +2,7 @@ package client
 
 import (
 	"context"
+	"errors"
 	"testing"
 
 	"github.com/golang/mock/gomock"
@@ -27,6 +28,49 @@ func TestSubmitAggregateAndProof_GetDutiesRequestFailure(t *testing.T) {
 	require.LogsContain(t, hook, "Could not fetch validator assignment")
 }
 
+func TestSubmitAggregateAndProof_SignFails(t *testing.T) {
+	validator, m, finish := setup(t)
+	defer finish()
+	validator.duties = &ethpb.DutiesResponse{
+		Duties: []*ethpb.DutiesResponse_Duty{
+			{
+				PublicKey: validatorKey.PublicKey.Marshal(),
+			},
+		},
+	}
+
+	m.validatorClient.EXPECT().DomainData(
+		gomock.Any(), // ctx
+		gomock.Any(), // epoch
+	).Return(&ethpb.DomainResponse{SignatureDomain: make([]byte, 32)}, nil /*err*/)
+
+	m.validatorClient.EXPECT().SubmitAggregateSelectionProof(
+		gomock.Any(), // ctx
+		gomock.AssignableToTypeOf(&ethpb.AggregateSelectionRequest{}),
+	).Return(&ethpb.AggregateSelectionResponse{
+		AggregateAndProof: &ethpb.AggregateAttestationAndProof{
+			AggregatorIndex: 0,
+			Aggregate: &ethpb.Attestation{
+				Data: &ethpb.AttestationData{
+					BeaconBlockRoot: make([]byte, 32),
+					Target:          &ethpb.Checkpoint{Root: make([]byte, 32)},
+					Source:          &ethpb.Checkpoint{Root: make([]byte, 32)},
+				},
+				Signature:       make([]byte, 96),
+				AggregationBits: make([]byte, 1),
+			},
+			SelectionProof: make([]byte, 96),
+		},
+	}, nil)
+
+	m.validatorClient.EXPECT().DomainData(
+		gomock.Any(), // ctx
+		gomock.Any(), // epoch
+	).Return(&ethpb.DomainResponse{SignatureDomain: nil}, errors.New("bad domain root"))
+
+	validator.SubmitAggregateAndProof(context.Background(), 0, validatorPubKey)
+}
+
 func TestSubmitAggregateAndProof_Ok(t *testing.T) {
 	validator, m, finish := setup(t)
 	defer finish()