Error in number formatting in case if thousands separator not specified

It appears, that number_format function seems to use "," as thousands separator even in case if thousands separator is not entered in language properties. By inspecting closely I've discovered, that ThousandsSep field in Language table has NULL value in case if empty value is entered in language properties. When NULL is given to number_format function, then is works as "," instead.

To fix this problem I propose to force type convert (to string) both decimal and thousands separator before passing them to number_format function.