Close to minimal case: https://gist.github.com/pnf/e208b0d44860aedc9c9d
Can't reproduce this particular report, however the flow filter error probably needs to be fixed.
Added test to verify this. https://github.com/clojure/core.typed/commit/f96d74a76fe72d26c06b1648df424f5314aa7cad
The general problem of the flow filter error still needs addressing.