Weird, your comment didn't show up before I posted mine. But yeah, looks like we are on the same path.

> If you want to handle exceptions here, I think perhaps it's best not to subclass from Hash at that point, and rather just use the Hash as an internal data structure like so:

Yeah, I think you're right. The other side-effect of subclassing is that I end up with a clone of `ENV` and not the original. I know _some people_ do crazy stuff with reloading `ENV` in unicorn.