Error TableGrid Version 3.5 If Value in Cell Is null ???

Error TableGrid Version 3.5 If Value in Cell Is null or '' ???

Old version Mysql when sql query   same tablegrid change result  all field is string  good work not error

but
later version 3.3   if database is mysql and table structure have number(decimal,double,integer) and value is null or = ''
ERROR  and not show result  in tablesgrid

Is bug ???

Script use

Form1.TableGrid1.ClearRows ;
Form1.TableGrid1.dbSQL := Form1.Memo1.Text;
Form1.TableGrid1.dbSQLExecute ;

I try test code why it error by edit in memo1.text

select  cast(null as char) as result

OK WORK and result '' in tablegrid

select  cast(null as Decimal) as result

Not OK ERROR

How To Fix result null if value = null