Fix verify_callback in the openssl s_client/s_server app
Fix verify_callback in the openssl s_client/s_server app

We need to check that error cert is available before printing its data

Reviewed-by: Tomas Mraz <2bc6038c3dfca09b2da23c8b6da8ba884dc2dcc2@openssl.org>
Reviewed-by: David von Oheimb <fbbca6c63636e78e7034aaf1b4aa3a9736383192@siemens.com>
Reviewed-by: Viktor Dukhovni <86faeb3e05561b856666236e198c27e698275e82@openssl.org>
Reviewed-by: Hugo Landau <ce9fa1e55a72fc9b85dd06e47ea2c07848fb7d2c@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18805)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl