CI4: query() now returns false for failed queries

[objecttothis]

https://codeigniter.com/user_guide/installation/upgrade_412.html#baseconnection-query-return-values

As of CI 4.1.2 query() returns false when a query fails. We may need to go through the code and add a check on the return value. Formerly I believe it returned an empty object. This function is used extensively in the models, so we need to think this one through.