Passing empty/no-op function to Route()?

[adam-p]

I'm trying to upgrade a dependency on 3.3.3 to the latest and I've hit a snag. We were passing nil to Router.Route()'s fn param so that later routes would get added as sub-routes to it. But as of this commit that causes a panic.

It looks like I can achieve the same thing by passing a no-op func instead of nil, but... is there something wrong with doing that? What was the reason for the change that added the panic? I don't want to naively bypass the panic and maybe reintroduce something bad that the panic was designed to detect.

Thanks.