Fixed!
Just add " ,null " to
$sql = $this->db->prepare( "SELECT * FROM {$this->popover} WHERE popover_active = 1 ORDER BY popover_order ASC" );
The FIXED code should look like this:
$sql = $this->db->prepare( "SELECT * FROM {$this->popover} WHERE popover_active = 1 ORDER BY popover_order ASC",null );
Let me know if it works for you.
Regards,
Chevyman