Apply suggestions from code review

Accept error handling suggestions.

Co-Authored-By: Eugene Kim <ek@harmony.one>

hmy/api_backend.go

@@ -364,10 +364,10 @@ func (b *APIBackend) GetValidatorSelfDelegation(addr common.Address) *big.Int {
 }
 
 // GetShardState ...
-func (b *APIBackend) GetShardState() *shard.State {
+func (b *APIBackend) GetShardState() (shard.State, error) {
 	state, err := b.hmy.BlockChain().ReadShardState(b.hmy.BlockChain().CurrentHeader().Epoch())
 	if err != nil {
-		return &shard.State{}
+		return nil, errors.Wrapf(err, "cannot read from DB")
 	}
-	return &state
+	return state, nil
 }

internal/hmyapi/backend.go

@@ -80,7 +80,7 @@ type Backend interface {
 	GetDelegationsByValidator(validator common.Address) []*staking.Delegation
 	GetDelegationsByDelegator(delegator common.Address) ([]common.Address, []*staking.Delegation)
 	GetValidatorSelfDelegation(addr common.Address) *big.Int
-	GetShardState() *shard.State
+	GetShardState() (shard.State, error)
 }
 
 // GetAPIs returns all the APIs.

internal/hmyapi/blockchain.go

@@ -518,11 +518,11 @@ func (s *PublicBlockChainAPI) GetValidatorInformation(ctx context.Context, addre
 		rpcValidator.TotalEffectiveStake = stats.TotalEffectiveStake.String()
 	}
 
-	shardState := s.b.GetShardState()
-	if shardState != nil {
+	shardState, err := s.b.GetShardState()
+	if err == nil {
 		blsKeyToShardID := make(map[shard.BlsPublicKey]uint32)
 
-		for _, committee := range *shardState {
+		for _, committee := range shardState {
 			for _, slot := range committee.Slots {
 				blsKeyToShardID[slot.BlsPublicKey] = committee.ShardID
 			}