Fix alert on tls1_process_alert failure.

If the function fails, it's an internal_error.

Change-Id: I4b7cf7a6ca2527f04b708303ab1bc71df762b55b
Reviewed-on: https://boringssl-review.googlesource.com/12312
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index a33562a..1b346d0 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -2007,9 +2007,14 @@
 
   /* TLS 1.3 session tickets are renewed separately as part of the
    * NewSessionTicket. */
-  int renew;
-  return tls_process_ticket(ssl, out_session, &renew, CBS_data(&ticket),
-                            CBS_len(&ticket), NULL, 0);
+  int unused_renew;
+  if (!tls_process_ticket(ssl, out_session, &unused_renew, CBS_data(&ticket),
+                          CBS_len(&ticket), NULL, 0)) {
+    *out_alert = SSL_AD_INTERNAL_ERROR;
+    return 0;
+  }
+
+  return 1;
 }
 
 int ssl_ext_pre_shared_key_add_serverhello(SSL *ssl, CBB *out) {