table: Return error if table reader is released
table: Return error if table reader is released

no2key/goleveldb,chai2010/goleveldb,conseweb/goleveldb,FactomProject/goleveldb,trigrass2/goleveldb,syndtr/goleveldb,btcsuite/goleveldb,hustbill/goleveldb,ngaut/goleveldb,rentongzhang/goleveldb,zzl0/goleveldb