Where to go to report a bug ??

Hi – When accessing my media library I got a whole page full of nasty error messages, all identical:

Warning: in_array() expects parameter 2 to be array, null given in C:\xampp\htdocs\Bees_Knees\wordpress\wp-includes\query.php on line 2399

the only way to clear it is to log out and back in again.

what do you do about this ?