$ret.code, $ret.token, $ret.msg

In version 8 and later syntax (syntaxversion pragma, here), the $ret.code, $ret.token, and $ret.msg variables are set by <sql> to the SQL result integer code, string token, and readable message, respectively, for the current iteration of the statement. These can be a more reliable way of checking success/failure than checking $loop. See here for details.