Did you want to have two separate asserts? One on the class, and another on depth?

Can you please elaborate a bit, or give an example? Notice that I've changed the code a bit in a new commit, but assert still in place.

This looks like it should be something more like:

assert true, "Recursive bordering is only supported for UIViews"
assert depth <= 0, "Recursive bordering requires a depth greater than 0"

There might be a misunderstanding here. The purpose of this assert is to make sure recursive bordering is not used for layers (or anything that's not a UIView or NSView). However regular bordering is still permitted for layers. So if you're in the code path that takes you to this else block, we should validate that depth is not provided to make sure recursive bordering won't happen.

I see. It reads like it's assert bad values on the depth, yet giving an unrelated error message.

I see. It reads like it asserts bad values on the depth, yet giving an unrelated error message.

Ok, I'll add a comment that should make it clearer.