The `err_cert` is not used anywhere in the function. The `X509_STORE_CTX_get_current_cert` is just a getter for `ctx->current_cert`:
```
X509 *X509_STORE_CTX_get_current_cert(X509_STORE_CTX *ctx)
	{
	return ctx->current_cert;
	}
```
It means that this line is useless. The only thing that it does is generating compiler warning about unused variable... :)