tls_error_vset
rv = tls_error_vset(error, errnum, fmt, ap);
rv = tls_error_vset(error, -1, fmt, ap);
rv = tls_error_vset(&config->error, errnum, fmt, ap);
rv = tls_error_vset(&config->error, -1, fmt, ap);
rv = tls_error_vset(&ctx->error, errnum, fmt, ap);
rv = tls_error_vset(&ctx->error, -1, fmt, ap);
rv = tls_error_vset(&ctx->error, -1, fmt, ap);