Fix: TJDBGridControl AV in design mode

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@2063 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/jujiboutils/src/jdbgridcontrol.pas

@@ -159,10 +159,13 @@ begin
   if Result <> nil then
   begin
     C := ColumnFromGridColumn(Column);
+    if C <> nil then
+    begin
       bs := C.ButtonStyle;
       aField := GetFieldFromGridColumn(Column);
       if (aField <> nil) and (bs = cbsAuto) then
       begin
+        writeln(aField.DataType);
         case aField.DataType of
           ftSmallint, ftInteger:
             Result := integerDbGridControl.Editor(Self);
@@ -183,6 +186,7 @@ begin
       end;
     end;
   end;
+end;
 
 procedure TJDBGridControl.UpdateData;
 begin