OSV-2021-1658 Null-dereference READ in istio.io/istio/security/pkg/util.ExtractJwtAud

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=42142 Crash type: Null-dereference READ Crash state: istio.io/istio/security/pkg/util.ExtractJwtAud...