If SELECT request specifies tuple count 0, no error

[Kostja Osipov]

If tuple count in SELECT packet is 0, the server does not reply with an error, but returns an empty result set.
Produce an error instead.

How to repeat:

An exemplary problematic request looks like below:

request type, 4 bytes = 17 (select)
body length, 4 bytes = 20
request id, 4 bytes = 0
namespace no, 4 bytes = 0
index_no, 4 bytes = 0
offset, 4 bytes = 0
limit, 4 bytes = MAX_INT
tuple count, 4 bytes = 0