Jannic Beck

I think the issue is probably a general type narrowing problem of the `TypeIs` implementation (so not directly an issue with the reachability analysis itself). At least I think that...

I was already thinking about submitting one, but I thought it is best to wait until it is confirmed (which you did just now ;) ) I will have a...

I checked the code in basedmypy and it seems that `covers_at_runtime` is using "only" `is_proper_subtype` (without erasing the generics). I think there are a few cases where this is not...