Add a notnull_check in s2n_kem_encapsulate() (#2152)
Add a notnull_check in s2n_kem_encapsulate() (#2152)

* Add a notnull_check in s2n_kem_encapsulate()

* Add a notnull_check in s2n_kem_decapsulate

Co-authored-by: Rodrigo Branco (BSDaemon) <11c9043035158e5d100393419faeea34b51558dd@amazon.com>
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