chore: fix inconsistent return results in consistency checker

[IronCore864]

Fix inconsistent return Results in consistency_checker.py.

Closes #120.

[benhoyt]

I can see what you mean, but I think this is a debatable: if there are no warnings, what's the advantage in having a variable at all over just passing []?

[tonyandrewmeyer]

I can see what you mean, but I think this is a debatable: if there are no warnings, what's the advantage in having a variable at all over just passing []?

I don't see a lot of merit in this, especially where the check method currently has no warnings at all.

The one advantage I can see is that if a method has a warning added, then it's less likely that it accidentally gets dropped in some cases if the code is updated like this proposal.

So I'm ok with this change - @IronCore864 if you're still keen on it, could you please merge or rebase to resolve the conflicts?

[tonyandrewmeyer]

I'm going to close this - @IronCore864 if you're still keen on it, could you please open it against the operator repo now that we've migrated there?