[node] fix print message if db already occupied

internal/shardchain/shardchains.go

@@ -77,7 +77,7 @@ func (sc *CollectionImpl) ShardChain(shardID uint32) (*core.BlockChain, error) {
 		// NewChainDB may return incompletely initialized DB;
 		// avoid closing it.
 		db = nil
-		return nil, errors.New("cannot open chain database")
+		return nil, errors.Wrap(err, "cannot open chain database")
 	}
 	if rawdb.ReadCanonicalHash(db, 0) == (common.Hash{}) {
 		utils.Logger().Info().

node/node.go

@@ -885,16 +885,15 @@ func New(
 		blockchain := node.Blockchain() // this also sets node.isFirstTime if the DB is fresh
 		beaconChain := node.Beaconchain()
 		if b1, b2 := beaconChain == nil, blockchain == nil; b1 || b2 {
-
-			shardID := node.NodeConfig.ShardID
-			// HACK get the real error reason
-			_, err := node.shardChains.ShardChain(shardID)
-
-			fmt.Fprintf(
-				os.Stderr,
-				"reason:%s beaconchain-is-nil:%t shardchain-is-nil:%t",
-				err.Error(), b1, b2,
-			)
+			var err error
+			if blockchain == nil {
+				shardID := node.NodeConfig.ShardID
+				// HACK get the real error reason
+				_, err = node.shardChains.ShardChain(shardID)
+			} else {
+				_, err = node.shardChains.ShardChain(shard.BeaconChainShardID)
+			}
+			fmt.Fprintf(os.Stderr, "Cannot initialize node: %v\n", err)
 			os.Exit(-1)
 		}