Err.PrivateSourcePrivate is used by Log_cli. We mean both libraries to work as companion libs. Note any of this can change without notice and without requiring a semver bump, so use at your own risk (or don't).
Since Err does not depend on Logs, the Err and Logs levels must be set independently. However, this is done for you consistently if you are using Log_cli.
To avoid making this library depend on Logs we inject the dependency into the functions we need instead. To be called with Logs.err_count and Logs.warn_count.