test(dataValidators): propagate NewUserAccount errors in bench stubs

Capture and return the error from state.NewUserAccount in the three
mock AccountsStub closures instead of discarding it. The error path
is only reachable on an empty address (not the case here), but the
defensive check matches the file's existing error-handling pattern
and silences the CodeRabbit nitpicks on PR #44.

Author: fbsobreira

core/process/dataValidators/txValidator_bench_test.go

@@ -55,7 +55,10 @@ func buildBenchValidator(tb testing.TB, numSigners int, keygenCost int) (process
 
 	adb := &mock.AccountsStub{
 		GetExistingAccountCalled: func(_ []byte) (state.AccountHandler, error) {
-			acc, _ := state.NewUserAccount(addressMock)
+			acc, err := state.NewUserAccount(addressMock)
+			if err != nil {
+				return nil, err
+			}
 			acc.Permissions = []*state.Permission{
 				{
 					Type:      state.Permission_Owner,
@@ -262,7 +265,10 @@ func BenchmarkCheckTxValidity_RealEd25519(b *testing.B) {
 			}
 			adb := &mock.AccountsStub{
 				GetExistingAccountCalled: func(_ []byte) (state.AccountHandler, error) {
-					acc, _ := state.NewUserAccount(sharedAddr)
+					acc, err := state.NewUserAccount(sharedAddr)
+					if err != nil {
+						return nil, err
+					}
 					acc.Permissions = []*state.Permission{
 						{Type: state.Permission_Owner, Threshold: 1, Signers: signers},
 					}
@@ -310,7 +316,10 @@ func TestBenchScaffolding_MultiSignerPathExecutes(t *testing.T) {
 	signers := []*state.Key{{Address: addressMock, Weight: 1}, {Address: addressMock, Weight: 1}}
 	adb := &mock.AccountsStub{
 		GetExistingAccountCalled: func(_ []byte) (state.AccountHandler, error) {
-			acc, _ := state.NewUserAccount(addressMock)
+			acc, err := state.NewUserAccount(addressMock)
+			if err != nil {
+				return nil, err
+			}
 			acc.Permissions = []*state.Permission{{Type: state.Permission_Owner, Threshold: 1, Signers: signers}}
 			return acc, nil
 		},