since #310, only the openssl backend has been added the capability to…

… detect supplied `key` being NULL, but how is that intended to work?

lib/openssl.c

@@ -1095,10 +1095,6 @@ static int aead_setup_crypto(ptls_aead_context_t *_ctx, int is_enc, const void *
     struct aead_crypto_context_t *ctx = (struct aead_crypto_context_t *)_ctx;
     int ret;
 
-    memcpy(ctx->static_iv, iv, ctx->super.algo->iv_size);
-    if (key == NULL)
-        return 0;
-
     ctx->super.dispose_crypto = aead_dispose_crypto;
     ctx->super.do_xor_iv = aead_xor_iv;
     if (is_enc) {
@@ -1138,6 +1134,8 @@ static int aead_setup_crypto(ptls_aead_context_t *_ctx, int is_enc, const void *
         goto Error;
     }
 
+    memcpy(ctx->static_iv, iv, ctx->super.algo->iv_size);
+
     return 0;
 
 Error: