Returns error for target (last request). The error code
is either a Z39.50 diagnostic code (usually a Bib-1
diagnostic) or a client side error code which is generated by
PHP/YAZ itself, such as "Connect failed", "Init Rejected",
etc.
yaz_errno() should be called
after network activity for each target - (after
yaz_wait() returns) to determine the success or
failure of the last operation (e.g. search). To get a text
description of the error, call
yaz_error().