Address coverity issue 1655295

Fixes: openssl/project#1267

Signed-off-by: Norbert Pocs <norbertp@openssl.org>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from openssl#27989)

Author: jogme

providers/implementations/keymgmt/ml_kem_kmgmt.c.in

@@ -542,7 +542,8 @@ void *ml_kem_load(const void *reference, size_t reference_sz)
     }
 
  err:
-    OPENSSL_secure_clear_free(encoded_dk, key->vinfo->prvkey_bytes);
+    if (key != NULL && key->vinfo != NULL)
+        OPENSSL_secure_clear_free(encoded_dk, key->vinfo->prvkey_bytes);
     ossl_ml_kem_key_free(key);
     return NULL;
 }