What is the best way to filter out invalid curves produced by a Fillet?

Hello all,

I've been working my way through my first definition - a system of units that vary in size - the form also has holes punched through it:

So far so good - as the size of each unit gets smaller, the holes get smaller:

The problem is that as individual units become very small, the Fillet operation starts to produce Invalid Curves, which wreak havoc further down the line:

What would be the best way to filter out these invalid curves, so that they're not passed along further in the definition, small panels simply don't have holes, and the final form remains valid? Would it be some sort of Dispatch directly after the Fillet that catches them? I'm not sure.

Thanks again for any help - much appreciated!

Elliot