Remove unneccesary code

Author: huangjunwen

replication/row_event.go

@@ -99,12 +99,7 @@ func (e *TableMapEvent) Decode(data []byte) error {
 
 pos += nullBitmapSize
 
-optionalMeta := data[pos:]
-if len(optionalMeta) == 0 {
-return nil
-}
-
-if err = e.decodeOptionalMeta(optionalMeta); err != nil {
+if err = e.decodeOptionalMeta(data[pos:]); err != nil {
 return err
 }