NULL checks for QUIC code
Fixes https://scan5.scan.coverity.com/#/project-view/62507/10222?selectedIssue=
1643033
Fixes https://scan5.scan.coverity.com/#/project-view/62507/10222?selectedIssue=
1643032
Fixes https://scan5.scan.coverity.com/#/project-view/62507/10222?selectedIssue=
1643031
Fixes https://scan5.scan.coverity.com/#/project-view/62507/10222?selectedIssue=
1643030
Fixes https://scan5.scan.coverity.com/#/project-view/62507/10222?selectedIssue=
1643029
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26825)