storage: panic on error in boltdb.Seek

Error in Seek means something is terribly wrong (e.g. db was not opened) and
error drop is not the right thing to do, because caller
will continue working with the wrong view.

pkg/core/storage/boltdb_store.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/etcd-io/bbolt"
-	log "github.com/sirupsen/logrus"
 	"github.com/syndtr/goleveldb/leveldb/util"
 )
 
@@ -109,7 +108,7 @@ func (s *BoltDBStore) Seek(key []byte, f func(k, v []byte)) {
 		return nil
 	})
 	if err != nil {
-		log.Error("error while executing seek in boltDB")
+		panic(err)
 	}
 }