When an analyzer calls DataIn(), there's a costly callback construct
going through the event queue. If an analyzer does not have a
get_file_handle() handler installed, the produced file_id would
end up empty and ignored. Consequently, the get_file_handle() callback
was invoked for every new DataIn() invocations.
This is surprising and costly. Log a warning when this happens and
instead set a generically generated file handle value instead to
prevent the repeated get_file_handle() invocations.
e4ab7b2d70