Should we error (or at least log a warning?) if aux methods have ambiguous order?

[camsaul]

If you have two :before methods that are both applicable but neither one is dominant over the other, the order they are applied is indeterminate. This matters for the threading method combinations because they can transform the value. :around methods can transform the value for the CLOS method combination as well (are we already erroring for :around methods?).

We should either error like we do for ambiguous primary methods or at least log a warning (probably just once)