User Stats has undocumented dependency on comment.module

Thanks very much for the bug report, apologies it has taken such a long time to get to it. I'm just having a think now about the best way to deal with this, as it raises a few fundamental questions about how we do things.

In the meantime, I'm marking #1678540: SQL error - User Stats assumes Comment module is enabled. a duplicate of this issue (just for reference: there's a patch on that issue, too).

This also causes an error in the D7 version

Can confirm this on D7. When disabling "Comment stats" check-box it seems to work fine. I think the requirement of Comment module is not necessary if no comment stats are needed